Posted by **Tony** on Friday, May 24, 2013 at 3:29pm.

If f(x) is a polynomial with real coefficients such that f(4+3i)=31+16i, then f(4−3i)=a+bi. What is the value of a+b

- Complex numbers -
**Steve**, Friday, May 24, 2013 at 4:04pm
f(x) = ax^n + bx^n-1 + ...

f(h+ki) = a(h+ki)^n + b(h+ki)^n-1 + ..

f(h-ki) = a(h-ki)^n + b(h-ki)^n-1 + ...

All of the even powers of i remain unchanged, and all of the odd powers of i change sign. So, the real part is unchanged, and the imaginary part changes sign.

f(4-3i) = 31-16i

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