Question

Give that y is directly proportional to x. if y =6, x = 2 . (a) find the value of k (b) calculate y when x = 7 (c) calculate x when y = 30​

Answer 1

see explanation

Explanation:

Given that y is directly proportional to x then the equation relating them is

y = kx ← k is the constant of proportion

(a)

To find k use the condition y = 6, x = 2, then

6 = 2k ( divide both sides by 2 )

k = 3

y = 3x ← equation of proportion

(b)

When x = 7, then

y = 3 × 7 = 21

(c)

When y = 30, then

30 = 3x ( divide both sides by 3 )

x = 10

Answer 2

Answer: (a) k = 3

(b) y = 21

(c) x = 10

Explanation:

Directly proportional uses the formula: y = kx

(a) Given y = 6 and x = 2, find k. 6 = k(2)

3 = k

(b) Given k = 3 and x = 7, find y. y = kx

y = 3(7)

y = 21

(c) Given k = 3 and y = 30, find x. y = kx

30 = 3x

10 = x