WAEC Mathematics 2020 Theory — Question 2

Model answer

(a)(i) P^(3/2) = rk/Q - ms. Add ms to both sides: P^(3/2) + ms = rk/Q. Multiply both sides by Q: Q(P^(3/2)+ms) = rk. Therefore, Q = rk / (P^(3/2) + ms). (ii) Substituting k=4, m=15, P=3, r=10, s=0.2: Q = (10x4) / (3^(3/2) + 15x0.2) = 40 / (5.196+3) = 40/8.196 = 4.88 (to 2 d.p). (b) x+2y=5x-10y. Firstly, divide both sides by y: x/y + 2 = 5x/y - 10. Collecting like terms: 5x/y - x/y = 2+10, giving 4x/y=12. Dividing both sides by 4: x/y = 3. Thus, x:y = 3:1.