SOLUTION: Can you help me solve this equation by completing the square? I am having a hard time figuring out the answer when the coefficient is not 1! 16x^2+40x+21=0 Thank you!

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Can you help me solve this equation by completing the square? I am having a hard time figuring out the answer when the coefficient is not 1! 16x^2+40x+21=0 Thank you!       Log On


   

Question 443613: Can you help me solve this equation by completing the square? I am having a hard time figuring out the answer when the coefficient is not 1!
16x^2+40x+21=0
Thank you!
Answer by swincher4391(1107) About Me  (Show Source):
You can put this solution on YOUR website!
Get it in the form ax^2 + bx = c
16x%5E2+%2B+40x+=+-21
16%28x%5E2+%2B+expr%285%2F2%29x%29+=+-21
%28x%5E2%2Bexpr%285%2F2%29x%29+=+-21%2F16
Now it is time to complete the square:
Recall that +c++=+%28b%2F2%29%5E2
So %285%2F4%29%5E2+=+25%2F16
Remember to balance the equation by adding what we added to complete the square to both sides.
%28x%5E2+%2B+5x+%2B+expr%2825%2F16%29%29+=+expr%28-21%2F16%29+%2B+25%2F16
%28x%2Bexpr%285%2F4%29%29%5E2+=+4%2F16
highlight%28%28x%2Bexpr%285%2F4%29%29%5E2+=+expr%281%2F4%29%29