Question

y=cos(-0.4x) has a horizontal stretch of..? PLEASE HELP

Answer 1

you mean period?

Answer 2

oh yes

Answer 3

are you looking for the period of
\[\cos(-.4x)\]?

Answer 4

yes

Answer 5

im looking for something like "it stretches X..."

Answer 6

period of
\[\cos(x)\] is
\[2\pi\] so period of
\[\cos(bx)\] is
\[\frac{2\pi}{b}\]

Answer 7

in your case you get
\[\frac{2\pi}{.4}=5\pi\]

Answer 8

no heres an example: y=-3cos1/2x has a horizontal stretch of 2
but i cant figure out what it would be for this problem

Answer 9

so period goes from 2 pi to 5 pi

Answer 10

oooooooooooooooh silly way to word the problem. in your case
\[\cos(\frac{1}{2}x)\] teh "stretch" was 2

Answer 11

in other words the reciprocal of coefficient. the reciprocal of .4 is 5, so stretch is 5

Answer 12

ohhhkay so you dont have to include the whole thing like 2/5=5/2 you just take the numerator?