Hello,

Question

I'm a little confused & not sure where I went wrong:
Solve the following systems of equations algebraically using the quadratic formula. Round answer to 2 decimal places.
y=-x^2+2x+9
y=-5x^2+10x+12
My work:

-x^2+2x+9=-5x+10x+12
Move everything from the right side to the left
4x^2-8x+7=0

x=(8+/- Root (64-4(4)(7)))/ 2(4)
My problem is that 64-4*4*7 is a negative number... Which makes me think I've made a wrong turn somewhere.

Thanks a bunch for your help! :)

Answer 1

-x^2+2x+9=-5x+10x+12
you mean
-x^2+2x+9=-5x^2 +10x+12 I am sure

whoops
9 - 12 = -3 not 7

Answer 2

4x^2-8x-3=0
[ 8 +/- sqrt 112 ]/8
I get 1 +/- .5 sqrt 7

Answer 3

Oh gosh! I dropped the 1 in 12... that's my whole problem. Thank you so much!