passwella.
Menu

WAEC Further Mathematics 2013 Question 20

Question 20

Functions

The function f : R → R is defined by f(x) = 3x + 2 : x > 4; 3x − 2 : x = 4; 5x − 3 : x < 4. Find f(4) − f(−3).

  1. A.28
  2. B.26
  3. C.−26
  4. D.−28
Show the answer and explanation

Answer: A (28)

Explanation

f(4) = 3(4) − 2 = 10 and f(−3) = 5(−3) − 3 = −18, so f(4) − f(−3) = 28.