Answer:
y = -1/2x^2 -5x -45/2
Step-by-step explanation:
Multiply it out and collect terms.
y = -1/2(x^2 +10x +25) -10 . . . . . expand the square
y = -1/2x^2 -5x -25/2 -20/2 . . . eliminate parentheses
y = -1/2x^2 -5x -45/2 . . . . . . . . collect terms
