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:
![image](https://i0.wp.com/78.media.tumblr.com/2227cc99230640de00e599813933b163/tumblr_inline_pc8ospGl4R1qio24w_540.png?w=852&ssl=1)
That’s still a line, but now the slope is –2a.
from Tumblr https://ift.tt/2LdY2wy