Question

Which of the following is the equation of the axis of symmetry of the quadratic equation y = 2(x + 7)2 - 4?

Answers:

x = 7

x = -4

x = 4

x = -7

Answer 1

What their really asking is what is the x value that splits the porabola equally in two halfs. You can find that by using the formula x=-b/2a which is essentialy the vertex of the porablola.

Answer 2

That formula is if the function above is expanded. In its factored form you can see that -7 is the vertext point.

Answer 3

\[x+7=0\]So x = ? is the axis of symmetry.. :)

Answer 4

You dont need to use that, in any function if you sum or subtract a number from x, you are simply changing the place of the parabola, and when you sum each x is equivalent to the x 7 units ahead, and the parabola is dislocated to the left, so if you are summing 7 you are dislocating the parabola 7 units to the left, and the simetry axis is clearly -7 without any math at all.

Answer 5

That is always true.