SOLUTION: x squared+8x+25=o choose one of the following as the answer A)-4+6i, -4-6i b)4+3i, 4-3i c)4+6i, 4-6i d)-4+3i, -4-3i

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: x squared+8x+25=o choose one of the following as the answer A)-4+6i, -4-6i b)4+3i, 4-3i c)4+6i, 4-6i d)-4+3i, -4-3i      Log On


   

Question 116981: x squared+8x+25=o
choose one of the following as the answer
A)-4+6i, -4-6i
b)4+3i, 4-3i
c)4+6i, 4-6i
d)-4+3i, -4-3i
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Let's use the quadratic formula to solve for x:


Starting with the general quadratic

ax%5E2%2Bbx%2Bc=0

the general solution using the quadratic equation is:

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29



So lets solve x%5E2%2B8%2Ax%2B25=0 ( notice a=1, b=8, and c=25)




x+=+%28-8+%2B-+sqrt%28+%288%29%5E2-4%2A1%2A25+%29%29%2F%282%2A1%29 Plug in a=1, b=8, and c=25



x+=+%28-8+%2B-+sqrt%28+64-4%2A1%2A25+%29%29%2F%282%2A1%29 Square 8 to get 64



x+=+%28-8+%2B-+sqrt%28+64%2B-100+%29%29%2F%282%2A1%29 Multiply -4%2A25%2A1 to get -100



x+=+%28-8+%2B-+sqrt%28+-36+%29%29%2F%282%2A1%29 Combine like terms in the radicand (everything under the square root)



x+=+%28-8+%2B-+6%2Ai%29%2F%282%2A1%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)



x+=+%28-8+%2B-+6%2Ai%29%2F%282%29 Multiply 2 and 1 to get 2



After simplifying, the quadratic has roots of

x=-4+%2B+3%2Ai or x=-4+-+3%2Ai


So the answer is D)