Question

If y varies inversely as x, what is k when y=8 and x=4

Answer 1

Answer:

k = 32

Step-by-step explanation:

If y varies inversely as x

Then y = k/x

y = 8, x = 4

8= k/4

Cross multiply

k = 8 × 4

k = 32

Answer 2

Step-by-step explanation:

Since, y varies inversely as x.

$\therefore \: y \:\alpha\: \frac{1}{x}\\\\ \therefore \: y =\frac{k}{x}\:\:\:(k = constant)\\\\ \therefore \: xy = k \\ when \: y=8 \: and \: x=4, \: k = ? \\ 4 \times 8 = k \\ \therefore \: k = 32$