Question

y^2 + y = 50

Answer 1

y = ( -1 +/- sqrt(201) )/2
... by quadratic formula

Answer 2

By completing the square:\[y ^{2}+y=50\]\[y ^{2}+y+1/4=50+1/4\]\[(y+1/2)^{2}=201/4\]\[y+1/2=\pm \sqrt{201}/2\]\[y=-1/2\pm \sqrt{201}/2\]