z^8=1+i (уравнение)

Учитель очень удивится увидев твоё верное решение 😼

Неизвестное в уравнении :

Искать численное решение на промежутке:

[, ]

    Найду корень уравнения: z^8=1+i

    Решение

    Вы ввели [src]
     8        
    z  = 1 + I
    z8=1+iz^{8} = 1 + i
    Подробное решение
    Дано уравнение
    z8=1+iz^{8} = 1 + i
    Т.к. степень в ур-нии равна = 8 и свободный член = 1 + i комплексное,
    зн. действительных решений у соотв. ур-ния не существует

    Остальные 8 корня(ей) являются комплексными.
    сделаем замену:
    w=zw = z
    тогда ур-ние будет таким:
    w8=1+iw^{8} = 1 + i
    Любое комплексное число можно представить так:
    w=reipw = r e^{i p}
    подставляем в уравнение
    r8e8ip=1+ir^{8} e^{8 i p} = 1 + i
    где
    r=216r = \sqrt[16]{2}
    - модуль комплексного числа
    Подставляем r:
    e8ip=2(1+i)2e^{8 i p} = \frac{\sqrt{2} \cdot \left(1 + i\right)}{2}
    Используя формулу Эйлера, найдём корни для p
    isin(8p)+cos(8p)=2(1+i)2i \sin{\left(8 p \right)} + \cos{\left(8 p \right)} = \frac{\sqrt{2} \cdot \left(1 + i\right)}{2}
    значит
    cos(8p)=22\cos{\left(8 p \right)} = \frac{\sqrt{2}}{2}
    и
    sin(8p)=22\sin{\left(8 p \right)} = \frac{\sqrt{2}}{2}
    тогда
    p=πN4+π32p = \frac{\pi N}{4} + \frac{\pi}{32}
    где N=0,1,2,3,...
    Перебирая значения N и подставив p в формулу для w
    Значит, решением будет для w:
    w1=216sin(π32)+216icos(π32)w_{1} = - \sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}
    w2=216sin(π32)216icos(π32)w_{2} = \sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}
    w3=216cos(π32)216isin(π32)w_{3} = - \sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}
    w4=216cos(π32)+216isin(π32)w_{4} = \sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}
    w5=2916sin(π32)2+2916cos(π32)2+2916isin(π32)2+2916icos(π32)2w_{5} = - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2}
    w6=2916sin(π32)2+2916cos(π32)22916icos(π32)2+2916isin(π32)2w_{6} = \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2}
    w7=2916cos(π32)22916sin(π32)22916isin(π32)2+2916icos(π32)2w_{7} = - \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2}
    w8=2916cos(π32)2+2916sin(π32)22916icos(π32)22916isin(π32)2w_{8} = - \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2}
    делаем обратную замену
    w=zw = z
    z=wz = w

    Тогда, окончательный ответ:
    z1=216sin(π32)+216icos(π32)z_{1} = - \sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}
    z2=216sin(π32)216icos(π32)z_{2} = \sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}
    z3=216cos(π32)216isin(π32)z_{3} = - \sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}
    z4=216cos(π32)+216isin(π32)z_{4} = \sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}
    z5=2916sin(π32)2+2916cos(π32)2+2916isin(π32)2+2916icos(π32)2z_{5} = - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2}
    z6=2916sin(π32)2+2916cos(π32)22916icos(π32)2+2916isin(π32)2z_{6} = \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2}
    z7=2916cos(π32)22916sin(π32)22916isin(π32)2+2916icos(π32)2z_{7} = - \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2}
    z8=2916cos(π32)2+2916sin(π32)22916icos(π32)22916isin(π32)2z_{8} = - \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} i \sin{\left(\frac{\pi}{32} \right)}}{2}
    График
    Быстрый ответ [src]
           16___    /pi\     16___    /pi\
    z1 = - \/ 2 *sin|--| + I*\/ 2 *cos|--|
                    \32/              \32/
    z1=216sin(π32)+216icos(π32)z_{1} = - \sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}
         16___    /pi\     16___    /pi\
    z2 = \/ 2 *sin|--| - I*\/ 2 *cos|--|
                  \32/              \32/
    z2=216sin(π32)216icos(π32)z_{2} = \sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}
           16___    /pi\     16___    /pi\
    z3 = - \/ 2 *cos|--| - I*\/ 2 *sin|--|
                    \32/              \32/
    z3=216cos(π32)216isin(π32)z_{3} = - \sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}
         16___    /pi\     16___    /pi\
    z4 = \/ 2 *cos|--| + I*\/ 2 *sin|--|
                  \32/              \32/
    z4=216cos(π32)+216isin(π32)z_{4} = \sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}
           / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\
           |2    *cos|--|   2    *sin|--||   2    *cos|--|   2    *sin|--|
           |         \32/            \32/|            \32/            \32/
    z5 = I*|------------- + -------------| + ------------- - -------------
           \      2               2      /         2               2      
    z5=2916sin(π32)2+2916cos(π32)2+i(2916sin(π32)2+2916cos(π32)2)z_{5} = - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + i \left(\frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right)
           / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\
           |2    *sin|--|   2    *cos|--||   2    *cos|--|   2    *sin|--|
           |         \32/            \32/|            \32/            \32/
    z6 = I*|------------- - -------------| + ------------- + -------------
           \      2               2      /         2               2      
    z6=2916sin(π32)2+2916cos(π32)2+i(2916cos(π32)2+2916sin(π32)2)z_{6} = \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right)
           / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\
           |2    *cos|--|   2    *sin|--||   2    *cos|--|   2    *sin|--|
           |         \32/            \32/|            \32/            \32/
    z7 = I*|------------- - -------------| - ------------- - -------------
           \      2               2      /         2               2      
    z7=2916cos(π32)22916sin(π32)2+i(2916sin(π32)2+2916cos(π32)2)z_{7} = - \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + i \left(- \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right)
           /   9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\
           |  2    *cos|--|   2    *sin|--||   2    *sin|--|   2    *cos|--|
           |           \32/            \32/|            \32/            \32/
    z8 = I*|- ------------- - -------------| + ------------- - -------------
           \        2               2      /         2               2      
    z8=2916cos(π32)2+2916sin(π32)2+i(2916cos(π32)22916sin(π32)2)z_{8} = - \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right)
    Сумма и произведение корней [src]
    сумма
                                                                                                                                                      / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\     / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\     / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\     /   9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\
                                                                                                                                                      |2    *cos|--|   2    *sin|--||   2    *cos|--|   2    *sin|--|     |2    *sin|--|   2    *cos|--||   2    *cos|--|   2    *sin|--|     |2    *cos|--|   2    *sin|--||   2    *cos|--|   2    *sin|--|     |  2    *cos|--|   2    *sin|--||   2    *sin|--|   2    *cos|--|
          16___    /pi\     16___    /pi\   16___    /pi\     16___    /pi\     16___    /pi\     16___    /pi\   16___    /pi\     16___    /pi\     |         \32/            \32/|            \32/            \32/     |         \32/            \32/|            \32/            \32/     |         \32/            \32/|            \32/            \32/     |           \32/            \32/|            \32/            \32/
    0 + - \/ 2 *sin|--| + I*\/ 2 *cos|--| + \/ 2 *sin|--| - I*\/ 2 *cos|--| + - \/ 2 *cos|--| - I*\/ 2 *sin|--| + \/ 2 *cos|--| + I*\/ 2 *sin|--| + I*|------------- + -------------| + ------------- - ------------- + I*|------------- - -------------| + ------------- + ------------- + I*|------------- - -------------| - ------------- - ------------- + I*|- ------------- - -------------| + ------------- - -------------
                   \32/              \32/            \32/              \32/              \32/              \32/            \32/              \32/     \      2               2      /         2               2           \      2               2      /         2               2           \      2               2      /         2               2           \        2               2      /         2               2      
    (2916cos(π32)2+2916sin(π32)2+i(2916cos(π32)22916sin(π32)2))(2916cos(π32)2+2916sin(π32)2i(2916sin(π32)2+2916cos(π32)2)i(2916sin(π32)2+2916cos(π32)2)i(2916cos(π32)2+2916sin(π32)2))\left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right)\right) - \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} - i \left(\frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right) - i \left(- \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right) - i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right)\right)
    =
      / 9/16    /pi\    9/16    /pi\\     / 9/16    /pi\    9/16    /pi\\     / 9/16    /pi\    9/16    /pi\\     /   9/16    /pi\    9/16    /pi\\
      |2    *cos|--|   2    *sin|--||     |2    *cos|--|   2    *sin|--||     |2    *sin|--|   2    *cos|--||     |  2    *cos|--|   2    *sin|--||
      |         \32/            \32/|     |         \32/            \32/|     |         \32/            \32/|     |           \32/            \32/|
    I*|------------- + -------------| + I*|------------- - -------------| + I*|------------- - -------------| + I*|- ------------- - -------------|
      \      2               2      /     \      2               2      /     \      2               2      /     \        2               2      /
    i(2916cos(π32)22916sin(π32)2)+i(2916cos(π32)2+2916sin(π32)2)+i(2916sin(π32)2+2916cos(π32)2)+i(2916sin(π32)2+2916cos(π32)2)i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right) + i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right) + i \left(- \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right) + i \left(\frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right)
    произведение
                                                                                                                                                  /  / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\\ /  / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\\ /  / 9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\\ /  /   9/16    /pi\    9/16    /pi\\    9/16    /pi\    9/16    /pi\\
                                                                                                                                                  |  |2    *cos|--|   2    *sin|--||   2    *cos|--|   2    *sin|--|| |  |2    *sin|--|   2    *cos|--||   2    *cos|--|   2    *sin|--|| |  |2    *cos|--|   2    *sin|--||   2    *cos|--|   2    *sin|--|| |  |  2    *cos|--|   2    *sin|--||   2    *sin|--|   2    *cos|--||
      /  16___    /pi\     16___    /pi\\ /16___    /pi\     16___    /pi\\ /  16___    /pi\     16___    /pi\\ /16___    /pi\     16___    /pi\\ |  |         \32/            \32/|            \32/            \32/| |  |         \32/            \32/|            \32/            \32/| |  |         \32/            \32/|            \32/            \32/| |  |           \32/            \32/|            \32/            \32/|
    1*|- \/ 2 *sin|--| + I*\/ 2 *cos|--||*|\/ 2 *sin|--| - I*\/ 2 *cos|--||*|- \/ 2 *cos|--| - I*\/ 2 *sin|--||*|\/ 2 *cos|--| + I*\/ 2 *sin|--||*|I*|------------- + -------------| + ------------- - -------------|*|I*|------------- - -------------| + ------------- + -------------|*|I*|------------- - -------------| - ------------- - -------------|*|I*|- ------------- - -------------| + ------------- - -------------|
      \           \32/              \32// \         \32/              \32// \           \32/              \32// \         \32/              \32// \  \      2               2      /         2               2      / \  \      2               2      /         2               2      / \  \      2               2      /         2               2      / \  \        2               2      /         2               2      /
    1(216sin(π32)+216icos(π32))(216sin(π32)216icos(π32))(216cos(π32)216isin(π32))(216cos(π32)+216isin(π32))(2916sin(π32)2+2916cos(π32)2+i(2916sin(π32)2+2916cos(π32)2))(2916sin(π32)2+2916cos(π32)2+i(2916cos(π32)2+2916sin(π32)2))(2916cos(π32)22916sin(π32)2+i(2916sin(π32)2+2916cos(π32)2))(2916cos(π32)2+2916sin(π32)2+i(2916cos(π32)22916sin(π32)2))1 \left(- \sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}\right) \left(\sqrt[16]{2} \sin{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \cos{\left(\frac{\pi}{32} \right)}\right) \left(- \sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} - \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}\right) \left(\sqrt[16]{2} \cos{\left(\frac{\pi}{32} \right)} + \sqrt[16]{2} i \sin{\left(\frac{\pi}{32} \right)}\right) \left(- \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + i \left(\frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right)\right) \left(\frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right)\right) \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + i \left(- \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2}\right)\right) \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} + \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2} + i \left(- \frac{2^{\frac{9}{16}} \cos{\left(\frac{\pi}{32} \right)}}{2} - \frac{2^{\frac{9}{16}} \sin{\left(\frac{\pi}{32} \right)}}{2}\right)\right)
    =
           -3*pi*I
           -------
      ___     4   
    \/ 2 *e       
    2e3iπ4\sqrt{2} e^{- \frac{3 i \pi}{4}}
    Численный ответ [src]
    z1 = 1.03924531873597 + 0.102356729874669*i
    z2 = -0.807234549989035 + 0.662480274400119*i
    z3 = 0.102356729874669 - 1.03924531873597*i
    z4 = -0.102356729874669 + 1.03924531873597*i
    z5 = -1.03924531873597 - 0.102356729874669*i
    z6 = 0.807234549989035 - 0.662480274400119*i
    z7 = 0.662480274400119 + 0.807234549989035*i
    z8 = -0.662480274400119 - 0.807234549989035*i