Question

Transformations help- pre calc. Hi I got a little confused with vertical stretches when I was asked this question: "Replace y with 2y in the function y= f(x)" The answer is a vertical stretch by a factor of 1/2. I know with horizontal stretches you use the reciprocal. But with this question instead of 'a' were given y? o.o. So 2= f(x)? and then I'm not sure where to go from there

Answer 1

Can you state an example?
It's hard to comprehend what you wanna know.

Answer 2

oh uhmmm, I'll write the full question. and some other examples: Describe what happens to the graph of a function y= f(x0 after the following changes are made to its equation:
A) replace y with 2y <--- my question

Example:
B) Replace x with 1/4x = horizontally stretched by a factor of 4

Answer 3

f(x) *

Answer 4

"A) replace y with 2y <--- my question"
Each y-coordinate of original graph gets divided by 2.
In other words "a vertical stretch by a factor of 1/2"

Answer 5

"B) Replace x with (1/4)x = horizontally stretched by a factor of 4"
That's correct

Answer 6

If it was written in an equation form how would look like? Do I leave the y isolated or? o.o or is "y= 2y" actually the f in y=f(x)? Sorry I'm pretty bad at math :P

Answer 7

I mean it would be y= af(x)? o.o

Answer 8

Please talk in terms of examples; it's hard to understand your words (no kidding)

"y= af(x)"
You can re-write it as
(1/a)y = f(x)

Answer 9

ohhh that's all I needed to know. Thanks :P

Answer 10

:)