WAEC Mathematics 2019 Objective — Question 17
Question 17 of 145 from the West African Examinations Council (WAEC) Mathematics 2019 Objective paper, with the correct answer and a full explanation.
Advertisement
17. If 3p = 4q and 9p = 8q − 12, find the value of pq.
- A. 12Correct
- B. 7
- C. -7
- D. -12
Explanation
From 3p=4q (i) and 9p=8q−12 (ii): multiplying (i) by 3 gives 9p−12q=0 (iii). Subtracting (iii) from (ii): 8q−12q−(−12q)=−12⇒ solving gives q=−3 and from (i), p = 4q/3 = −4. So pq = (−4)(−3) = 12.
Advertisement
Sign up free to unlock
- Score tracking
- Practice history
- Saved questions
- Progress dashboard
- Personalized sessions
- Weak-topic breakdown
…and/or go further with premium services and No Ads.