Question

How do you solve `2x^{2}-2x+21=(x-4)^{2}`?

Answer 1

`x_1=-5` and `x_2=-1`

Explanation:

`2x^2-2x+21=(x-4)^2`

`2x^2-2x+21=x^2-8x+16`

`x^2+6x+5=0`

`(x+5)*(x+1)=0`

Hence `x_1=-5` and `x_2=-1`