SOLUTION: Solve 8x2 + 6x + 5 = 0.

Algebra ->  Linear-equations -> SOLUTION: Solve 8x2 + 6x + 5 = 0.      Log On


   

Question 916678: Solve 8x2 + 6x + 5 = 0.
Answer by josh_jordan(263) About Me  (Show Source):
You can put this solution on YOUR website!
8x%5E2%2B6x%2B5=0

You will use the quadratic formula to solve for x. Recall that the quadratic formula is as follows: x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

x=%28-6%2B-sqrt%286%5E2-4%2A8%2A5%29%29%2F%282%2A8%29----->

x=%28-6%2B-sqrt%2836-160%29%29%2F%2816%29----->

x=%28-6%2B-sqrt%28-124%29%29%2F%2816%29

At this point, we will be using imaginary numbers, since the number inside the square root is negative. When we factor 124, we see that 4 x 31 = 124. We can then reduce the root to 2i%2Asqrt%2831%29. We now have

x=%286%2B-2i%2Asqrt%2831%29%29%2F%2816%29 (Ignore the ( between the +- symbol. It automatically formatted that way)

Next, we can factor out a 2 from the numerator, reducing our numerator and denominator to the following, which is our final answer:

x=%28-3%2Bi%2Asqrt%2831%29%29%2F%288%29,%28-3-i%2Asqrt%2831%29%29%2F%288%29