help test tomorrow

[scooter98]

we have begin working this problem and the book has a different answer. Someone please help.

f(x)= 2xsquared + 4x -6 find vertex and axis of symmetry

heres what we have

2(xsquared + 2X -3)
2(xsquared + 2x +1squared - 3 - 1squared)
2(xsquared +2x + 1squared) + 2(-3 - 1)
2(x+1)squared -8


the book has 2(x-1)-8

 

[skeeter]

f(x) = 2x² + 4x - 6

x-value for the axis of symmetry is x = -b/(2a) = -4/4 = -1

y-value for the axis of symmetry is y = f(-1) = -8

using the vertex form, f(x) = a(x - h)² + k

can be rewritten as f(x) = 2(x + 1)² - 8