I have the equation $\sqrt{(7-x)} - \sqrt {(x+13)} = 2 $ The square root should be expanded so it is square root of $7-x$ - square root of $x+13 = 2$. When i square both sides i get: $7-x - x-13 = 4 $
then i clean on the LHS so i get $-2x-6 = 4$ which leads to $(-2x-6)^2 = 4^2$ and after working that out i get:
$4x^2 + 24 x + 36 = 16$.
Next step will then be $4x^2 +24x +20 = 0$
Using the pq formula i get $x^2 = -6/2$ +- $\sqrt {6 \over 2}^2 -5$
And after that i get $x^2 = -6/2 +- 2$ which leads to $x^2 = -1$ or $x^2= -5$.
The answer according to the textbook is $-9$. Do you know how to solve this ?