If f(x) = 13x - 21 and f(x) = -112, find x.

Answer 1

Because f(x) equals both 13x-21 and -112, 13x-21 must = -112

13x-21 = -112

To solve, isolate x. To get x by itself, we have to get rid of the 13 in front of the x and the 21. We get rid of the 21 first, since this is like an outer defense protecting the x. Once we get rid of the 21, then we can move inward and get rid of the 13.

The 21 is being subtracted, so to get rid of it, add 21 to both sides.

13x = -112 + 21

13x = -91

Next, get rid of the 13. The 13 is being multiplied, so to get rid of it we divide 13 to both sides

x = -91/13 = -7

Therefore x = -7