Asked by #Thanks

The roots of the quadratic equation z^2 + az + b = 0 are 2 - 3i and 2 + 3i. What is a+b
Answered by Damon
(z - 2 +3i)(z -2 -3i) = 0
commutative property to multiply

z (z -2 -3i) = z^2 -2 z -3 z i
-2(z -2 -3i) = -2 z + 4 + 6 i
3i(z -2 -3i) = +3zi -6 i + 9
add ------------------------------

= z^2 - 4 z + 13
so
a = -4 and b = 9

Answered by #Thanks
I input 5 but I said it was wrong.
Answered by #Thanks
I input 5 but it said it was wrong
Answered by Steve
duh

there was a typo and you missed it. Always check the answers you find.
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