Question

PRACTISE NOW 6
1. If y is directly proportional to x and y = 18 when x = 3,
(i) find an equation connecting x and y,
(ii) find the value of y when x = 5,
(iii) calculate the values of x when y = 32,​

Answer 1

Answer:

(i) y = 6x; (ii) 30; (iii) 16/3

Step-by-step explanation:

"y" is directly proportional to "x" if there is non-zero constant "k" such that

y = kx ===> k = y/x for any x ≠ 0 .

The relation is often denoted using the symbols "∝" or "~" :

y ∝ x or y ~ x .

1. k = 18 / 3 = 6

(i) y = 6x

(ii) y = 6 × 5 = 30

(iii) 32 = 6x ===> x = 32/6 = 16/3