Question

Which table contains the vertex of the graph represented by y=x^2-6x+4?

X. Y
-2 20
0 4
2 -4
4 -4


X. Y
-1 11
1. -1
3. -5
6. 4

X. Y
-3. 31
-1. 12
0. 4
2 12

X. Y
0 5
2 7
3. 5
5. 7

Answer 1

vertex = (3,- 5 )

given a quadratic in standard form : y = ax² + bx + c ( a ≠ 0 ), then

the x-coordinate of the vertex is

`x_(vertex)` = -
`(b)/(2a)`

y = x² - 6x + 4 is in standard form

with a = 1, b = - 6 and c = 4, hence

`x_(vertex)` = -
`(-6)/(2)` = 3

substitute this value into the equation for y- coordinate

y = 3² - 6(3) + 4 = 9 - 18 + 4 = - 5

vertex = (3, - 5 ) → second table