Question

Convert y = 15x^2 - 300x - 60 vertex form by completing the square​

Answer 1

Explanation:

y=15 x²-300 x-60

=15(x²-20 x)-60

=15(x²-20 x+(-20/2)²-(20/2))-60

=15(x²-20 x+100-100)-60

=15(x²-20x+100)-1500-60

=15(x-10)²-1560

vertex is (10,-1560)

Answer 2

y = 15(x -10)^2 -1560

Explanation:

It usually works well to divide the leading coefficient from the x terms:

y = 15(x^2 -20x) -60

Now, add the square of half the x-coefficient inside parentheses. Subtract the same amount outside.

y = 15(x^2 -20x +100) -60 -(15)(100)

y = 15(x -10)^2 -1560 . . . . . collect terms; write the parentheses as a square