Question

Question 3 of 10

Which of the following functions best describes this graph?
6
-5
O A. y=x2-9x+ 20
O B. y = x2 + 9x+ 20
O C. y= x2 + x - 12
O D. y= x2 - 8x+18

Answer 1

A

Explanation:

you can find the vertex of each equation and then compare to the graph

x = -b/2a

A) x = -(-9)/2(1); x = 9/2 or x = 4 1/2

plug 4 1/2 into equation as 'x' to find 'y'

y = (9/2)² - 9(9/2) + 20

y = 81/4 - 81/2 + 20

y = 81/4 - 162/4 + 80/4

y = -81/4 + 80/4

y = -1/4

the only option with a vertex at (9/2, -1/4) is A