4x^2+8x=7
Minus the 7, and use the quadradic formula? cause i couldnt factor it. Its been a while, somebody will help you though so dont worry. But once you get the values for x, you plug them into the original problem and see if it equals 7.
a = 4, b = 8 , c= -7
here is what i got for the exact values.
0.6583123951776999
-2.6583123951776999
You decide which one it is.