Question

-2x^2+x+7=x^2+5x+(-2-x)^2

Answer 1

- 2x^2 + x + 7 = x^2 + 5x + x^2 + 4x + 4
- 2x^2 + x + 7 = 2x^2 + 9x + 4
- 2x^2 + x + 7 - 2x^2 - 9x - 4 = 0 
- 4x^2 - 8x + 3 = 0 
4x^2 + 8x - 3 = 0 
D = 64 + 48 = 112
√D = √(16*7) = 4√7

x₁ = ( - 8 + 4√7)/8 = - 1 + √7/2; 
x₂ = ( - 8 - 4√7)/8 = - 1 - √7/2;