Note that *f*(*x*) is a line in slope-intercept form, where *a* is the slope and *b* is the intercept.

Once you recognize that, you just need to know that, notationally, the –2 in front of *f*(*x*) means you multiply the whole thing by –2. So:

That’s still a line, but now the slope is –2*a*.

from Tumblr https://ift.tt/2LdY2wy