Question

If you apply the changes below to the quadratic parent function, f(x) = x²,

which of these is the equation of the new function? Shift 1 unit left.

Vertically stretch by a factor of 5.
Reflect over the x-axis.
A. g(x) = -5(x-1)²
B. g(x) = -5x² - 1
C. g(x) = -5(x + 1)²
D. g(x) = (-5x + 1)²

Answer 1

Explanation:

Comment

Do the most mechanical part first. Moving 1 unit left will mean that x becomes (x + 1). It is anti intuative, but that is the correct answer.

So far what you have is y = a(x + 1)^2

The reason that you want to do it this way is any answer with a minus sign is wrong which eliminates A and B

When you stretch the parabola, a becomes 5 so now you have another part of the puzzle. and the equation becomes

y = 5(x + 1)^2

The 5 goes on the outside of the brackets which eliminates D

When you reflect this over the x axis, you invert the parabola which means you turn it upside down. The sign in front of the 5 becomes a minus.

Answer

y = - 5(x + 1)^2 or C.