SOLUTION: If x+iy=(a+ib)*(a+ib)*(a+ib) then show that x/a+y/b=4(a^2-b^2) PLZ help!!!!

Algebra.Com
Question 319748: If x+iy=(a+ib)*(a+ib)*(a+ib) then show that x/a+y/b=4(a^2-b^2)
PLZ help!!!!

Answer by J2R2R(94)   (Show Source): You can put this solution on YOUR website!
x+iy = (a+ib)^3 = a^3 + 3a^2ib + 3ai^2b^2 + i^3b^3 = (a^3 - 3ab^2) + (3a^2b - b^3)i

Comparing real and imaginary components:
x = a^3 - 3ab^2; x/a = a^2 - 3b^2
y = 3a^2b - b^3; y/b = 3a^2 - b^2

x/a + y/b = 4(a^2 - b^2)

RELATED QUESTIONS

Given that √(x + iy) = a + ib, so that x = a^2 + b^2, y = 2ab and find a and b if x (answered by ikleyn)
(a+ib)(a-ib) (answered by rahman)
(a+ib)^2 (answered by atif.muhammad)
1.If (a+ib)/(c+id)=A+iB ,then prove that... (answered by CharlesG2)
Q.1 If {{{ (x+iy)^(1/3)=a+ib }}} then show that {{{ 4(a^2 - b^2)=x/a + y/b }}} Q.2... (answered by KMST)
Show that... (answered by tommyt3rd)
Express (x + iy)(u - iv)(x - iy)(u + iv) in the form a + ib, where a, b €... (answered by MathLover1)
Express 4-3i/2+i in the form... (answered by mananth)
What is the conjugate of... (answered by stanbon)