Question

Which equation shows direct variation?

a) a = 5/b
b) a = 5 * b
c) a + b = 5
d) a - b = 5

Answer 1

Our answer is b) a = 5 * b

`\Large\texttt{Explanation}`

We are asked to determine which equation shows direct variation.

Direct Variation

When two numbers/variables vary directly, this is called direct variation, and it's written as y = kx, where k = constant of proportionality and y and x are two variables that vary directly.

Similarly, if a and b vary directly, we write it as a = k * b.

The choice that shows direct variation is b). (where the value of k is 5)

`\therefore` our answer is a = 5 * b

Answer 2

(b)

Explanation:

2 quantities x and y in direct variation are related as

y = kx ← k is the constant of variation

the only equation in this form from the list is

a = 5b with k = 5