WAEC Further Mathematics 2022 Objective — Question 6

Question 6 of 40 from the West African Examinations Council (WAEC) Further Mathematics 2022 Objective paper, with the correct answer and a full explanation.

The functions f:x→5x²+7x−6 and g:x→2x²+3x−7 are defined on the set of real numbers, R. Find the values of x for which 3f(x)=g(x).

A. x=−3 or −5
B. x=3 or −5Correct
C. x=3 or −5
D. x=3 or 5

Explanation

3f(x)=g(x) gives 3(2x²+3x−7)... actually 3(5x²+7x−6)... solving 6x²+9x−21=5x²+7x−6 leads to x²+2x−15=0, i.e. (x−3)(x+5)=0, so x=3 or x=−5.

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