SOLUTION: Complete the square to write the quadratic function in vertex form. y = x^2 + 8x + 1

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Complete the square to write the quadratic function in vertex form. y = x^2 + 8x + 1      Log On


   

Question 811506: Complete the square to write the quadratic function in vertex form.
y = x^2 + 8x + 1
Answer by erica65404(394) About Me  (Show Source):
You can put this solution on YOUR website!
complete the square
ax%5E2+%2B+bx+%2B+c
ax%5E2+%2B+bx+%2B+%28%281%2F2%29b%29%5E2+-+%28%281%2F2%29b%29%5E2+%2B+c
%28x+%2B+%281%2F2%29b%29%5E2+%2B+c+-+%28%281%2F2%29b%29%5E2
That probably looks a little complicated, so i will explain it.
y+=+x%5E2+%2B+8x+%2B+1
take half of 8 (4)
and square it. (4*4)
then add and subtract it into the equation
y+=+x%5E2+%2B+8x+%2B+16+-+16+%2B+1
now take %28x%5E2+%2B+8x+%2B+16%29
this can be factored into
%28x%2B4%29%5E2
then you just add on the rest
%28x%2B4%29%5E2-15
this is the vertex form
and your vertex is (-4,-15)