The parabola y=x^2

Question

How can that equation be changed to shift the parabola three units to the left and five units down

Answer 1

vertex was at (0,0)
now at (-5,-3)

(y+3) = (x+5)^2

y + 3 = x^2 + 10 x + 25

y = x^2 + 10 x + 22

Answer 2

Where did the 10 come from ? 3^2 is 9