Mister Exam

Other calculators

z^4=i equation

The teacher will be very surprised to see your correct solution 😉

v

Numerical solution:

Do search numerical solution at [, ]

The solution

You have entered [src]
 4    
z  = I
z4=iz^{4} = i
Detail solution
Given the equation
z4=iz^{4} = i
Because equation degree is equal to = 4 and the free term = i complex,
so the real solutions of the equation d'not exist

All other 4 root(s) is the complex numbers.
do replacement:
w=zw = z
then the equation will be the:
w4=iw^{4} = i
Any complex number can presented so:
w=reipw = r e^{i p}
substitute to the equation
r4e4ip=ir^{4} e^{4 i p} = i
where
r=1r = 1
- the magnitude of the complex number
Substitute r:
e4ip=ie^{4 i p} = i
Using Euler’s formula, we find roots for p
isin(4p)+cos(4p)=ii \sin{\left(4 p \right)} + \cos{\left(4 p \right)} = i
so
cos(4p)=0\cos{\left(4 p \right)} = 0
and
sin(4p)=1\sin{\left(4 p \right)} = 1
then
p=πN2+π8p = \frac{\pi N}{2} + \frac{\pi}{8}
where N=0,1,2,3,...
Looping through the values of N and substituting p into the formula for w
Consequently, the solution will be for w:
w1=24+12+i24+12w_{1} = - \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}} + i \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}}
w2=24+12i24+12w_{2} = \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}} - i \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}}
w3=24+12i24+12w_{3} = - \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}} - i \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}}
w4=24+12+i24+12w_{4} = \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}} + i \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}}
do backward replacement
w=zw = z
z=wz = w

The final answer:
z1=24+12+i24+12z_{1} = - \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}} + i \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}}
z2=24+12i24+12z_{2} = \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}} - i \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}}
z3=24+12i24+12z_{3} = - \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}} - i \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}}
z4=24+12+i24+12z_{4} = \sqrt{\frac{\sqrt{2}}{4} + \frac{1}{2}} + i \sqrt{- \frac{\sqrt{2}}{4} + \frac{1}{2}}
The graph
Sum and product of roots [src]
sum
     ___________        ___________      ___________        ___________        ___________        ___________      ___________        ___________
    /       ___        /       ___      /       ___        /       ___        /       ___        /       ___      /       ___        /       ___ 
  \/  2 - \/ 2     I*\/  2 + \/ 2     \/  2 - \/ 2     I*\/  2 + \/ 2       \/  2 + \/ 2     I*\/  2 - \/ 2     \/  2 + \/ 2     I*\/  2 - \/ 2  
- -------------- + ---------------- + -------------- - ---------------- + - -------------- - ---------------- + -------------- + ----------------
        2                 2                 2                 2                   2                 2                 2                 2        
(2+22+i2+22)+(2+22i2+22)+(2+22i2+22)+(2+22+i2+22)\left(- \frac{\sqrt{- \sqrt{2} + 2}}{2} + \frac{i \sqrt{\sqrt{2} + 2}}{2}\right) + \left(\frac{\sqrt{- \sqrt{2} + 2}}{2} - \frac{i \sqrt{\sqrt{2} + 2}}{2}\right) + \left(- \frac{\sqrt{\sqrt{2} + 2}}{2} - \frac{i \sqrt{- \sqrt{2} + 2}}{2}\right) + \left(\frac{\sqrt{\sqrt{2} + 2}}{2} + \frac{i \sqrt{- \sqrt{2} + 2}}{2}\right)
=
0
00
product
     ___________        ___________      ___________        ___________        ___________        ___________      ___________        ___________
    /       ___        /       ___      /       ___        /       ___        /       ___        /       ___      /       ___        /       ___ 
  \/  2 - \/ 2     I*\/  2 + \/ 2     \/  2 - \/ 2     I*\/  2 + \/ 2       \/  2 + \/ 2     I*\/  2 - \/ 2     \/  2 + \/ 2     I*\/  2 - \/ 2  
- -------------- + ---------------- * -------------- - ---------------- * - -------------- - ---------------- * -------------- + ----------------
        2                 2                 2                 2                   2                 2                 2                 2        
(2+22+i2+22)(2+22i2+22)(2+22i2+22)(2+22+i2+22)\left(- \frac{\sqrt{- \sqrt{2} + 2}}{2} + \frac{i \sqrt{\sqrt{2} + 2}}{2}\right) * \left(\frac{\sqrt{- \sqrt{2} + 2}}{2} - \frac{i \sqrt{\sqrt{2} + 2}}{2}\right) * \left(- \frac{\sqrt{\sqrt{2} + 2}}{2} - \frac{i \sqrt{- \sqrt{2} + 2}}{2}\right) * \left(\frac{\sqrt{\sqrt{2} + 2}}{2} + \frac{i \sqrt{- \sqrt{2} + 2}}{2}\right)
=
-I
i- i
Rapid solution [src]
           ___________        ___________
          /       ___        /       ___ 
        \/  2 - \/ 2     I*\/  2 + \/ 2  
z_1 = - -------------- + ----------------
              2                 2        
z1=2+22+i2+22z_{1} = - \frac{\sqrt{- \sqrt{2} + 2}}{2} + \frac{i \sqrt{\sqrt{2} + 2}}{2}
         ___________        ___________
        /       ___        /       ___ 
      \/  2 - \/ 2     I*\/  2 + \/ 2  
z_2 = -------------- - ----------------
            2                 2        
z2=2+22i2+22z_{2} = \frac{\sqrt{- \sqrt{2} + 2}}{2} - \frac{i \sqrt{\sqrt{2} + 2}}{2}
           ___________        ___________
          /       ___        /       ___ 
        \/  2 + \/ 2     I*\/  2 - \/ 2  
z_3 = - -------------- - ----------------
              2                 2        
z3=2+22i2+22z_{3} = - \frac{\sqrt{\sqrt{2} + 2}}{2} - \frac{i \sqrt{- \sqrt{2} + 2}}{2}
         ___________        ___________
        /       ___        /       ___ 
      \/  2 + \/ 2     I*\/  2 - \/ 2  
z_4 = -------------- + ----------------
            2                 2        
z4=2+22+i2+22z_{4} = \frac{\sqrt{\sqrt{2} + 2}}{2} + \frac{i \sqrt{- \sqrt{2} + 2}}{2}
Numerical answer [src]
z1 = -0.38268343236509 + 0.923879532511287*i
z2 = -0.923879532511287 - 0.38268343236509*i
z3 = 0.38268343236509 - 0.923879532511287*i
z4 = 0.923879532511287 + 0.38268343236509*i
z4 = 0.923879532511287 + 0.38268343236509*i