What is the vertex form of y = x^2 - 20x + 15

So your equation is y = x² - 20x + 15. what you'll want to do is complete the square, so take half of 20 and square it. 20/2 = 10. 10² = 100. add 100 to both sides. and simplify x²-20x+100+15 to (x²-10) ²+15. now subtract 100 from both sides to get y alone. this leaves you with y = (x²-10) - 85. that's your vertex form.

Given a function:

y=ax²-bx+c

The vertex is: (-b/2a, f (-b/2a)

In this case:

y=x²-20x+15

-b/2a=20/2=10

f (10) = 10²-20 (10) + 15=100-200+15=-85

Answer: The vertex is (10,-85)

Given a vertex (h, k), the vertex form is:

y=a (x-h) ²+k

In this case:

(10,-85)

a=1

y = (x-10) ²-85

Answer: y = (x-10) ²-85