Question 720317
√(x + 7) - 2√(x) = -2 
√(x+7)=2√x-2
square both sides
x+7=4x-8√x+4
-3x+3=-8√x
-3(x-1)=-8√x
square both sides again
9(x-1)^2=64x
9(x^2-2x+1)=64x
9x^2-18x+9-64x=0
9x^2-82x+9=0
solve for x using quadratic formula:
x≈0.1111..(reject, extraneous root)
x=9