156k views
25 votes
How is the graph of the parent quadratic function transformed to produce the graph of y=-(2x+6)²+3?

The graph is compressed horizontally by a factor of 2, shifted left 3 units, reflected over the x-axis, and translated
up 3 units.
The graph is reflected over the x-axis, compressed horizontally by a factor of 2, shifted left 6 units, and translated
up 3 units.
The graph is stretched horizontally by a factor of 2, reflected over the x-axis, shifted left 3 units, and translated up
3 units.
The graph is reflected over the x axis, stretched horizontally by a factor of 2, shifted left 6 units, and translated up
3 units.

User Ljmelgui
by
3.7k points

1 Answer

7 votes

Answer:

(a) The graph is compressed horizontally by a factor of 2, shifted left 3 units, reflected over the x-axis, and translated up 3 units

Explanation:

The transformations under discussion here are ...

  • y = k·f(x) . . . . . . reflection over x-axis when k=-1
  • y = f(kx) . . . . . . horizontal compression by a factor of k
  • y = f(x -k) . . . . . right shift by k units
  • y = f(x) +k . . . . translation upward by k units.

__

application

The application of these transformations is a bit easier to see if we rewrite the transformed function to ...

y = -(2(x -(-3)))² +3

The leading minus sign shows a reflection over the x-axis.

The factor of 2 shows a horizontal compression by a factor of 2.

The subtraction of -3 from x shows a translation left of 3 units. (Right by -3 units.)

The addition of 3 to the function value shows a translation upward of 3 units.

__

summary

The combined transformation can be described as ...

The graph is compressed horizontally by a factor of 2, shifted left 3 units, reflected over the x-axis, and translated up 3 units.

_____

Additional comment

The base of the square can be obtained by either of these methods:

x² ⇒ (x +6)² ⇒ (2x +6)² . . . translated left 6 units, then the translated function compressed by a factor of 2

x² ⇒ (2x)² ⇒ (2(x +3))² . . . compressed by a factor of 2, then translated left 3 units.

We choose to present the translation last, because it seems more obvious when looking at the graph. The parent vertex is at x=0; the transformed vertex is at x=-3, an apparent translation of -3 units.

It takes more mental effort to understand this is the same as translation -6 units, then compression by a factor of 2, wherein the compression also affects the translation.

How is the graph of the parent quadratic function transformed to produce the graph-example-1
User Elssar
by
4.3k points