Question

Which functions have an axis of symmetry of x = –2? Check all that apply.

f(x) = x2 + 4x + 3
f(x) = x2 – 4x – 5
f(x) = x2 + 6x + 2
f(x) = –2x2 – 8x + 1
f(x) = –2x2 + 8x – 2

Answer 1

the answer is the first one and the fourth one 

Answer 2

Answer :
`Answer :f(x) = x^2 + 4x + 3 \ and \ f(x) = -2x^2 - 8x + 1`

Given: axis of symmetry of x = –2

To find axis of symmetry we use formula
`x =(-b)/(2a)`

We check which equation has axis of symmetry x= -2

(1)
`f(x) = x^2 + 4x + 3`

a=1 , b=4 so axis of symmetry
`x =(-4)/(2*1) = -2`

(2)
`f(x) = x^2 - 4x - 5`

a=1 , b=-4 so axis of symmetry
`x =(-(-4))/(2*1) = 2`

(3)
`f(x) = x^2 + 6x + 2`

a=1 , b=6 so axis of symmetry
`x =(-6)/(2*1) = -3`

(4)
`f(x) = -2x^2 - 8x + 1`

a=-2 , b=-8 so axis of symmetry
`x =(-(-8))/(2*(-2)) = -2`

(5)
`f(x) = -2x^2 + 8x - 2`

a=-2 , b=8 so axis of symmetry
`x =(-(8))/(2*(-2)) = 2`

So
`f(x) = x^2 + 4x + 3` and
`f(x) = -2x^2 - 8x + 1` has axis of symmetry x=-2