f(x) = |7m + 4| = 1
First equation by taking positive modules
7m + 4 = 1
7m = -3
m = -3/7 . Ans.
Second equation by taking negative modules
-7m - 4 = 1
-7m = 5
m = -5/7 . Ans.
∴ m = [ -5/7 U -3/7 ] Ans .
