Question

Given that y varies inversely with x, if x =7 and y = 4, what is y when x = 2?

Answer 1

Answer:

$y=14$

Step-by-step explanation:

$y \propto 1/x$

$y=k/x$

$4=k/7$

$4 \times 7 = k$

$28=k$

$y=28/x$

$y=28/(2)$

$y=14$

Answer 2

Answer:

y = 14

Step-by-step explanation:

y ∝ $\frac{1}{x}$

=> y = $\frac{k}{x}$     -------------(1)

Where k is the constant of proportionality

Now,

x = 7, y = 4

Putting in (1)

4 = $\frac{k}{7}$

So,

=> k = 28

Now y = ? when x = 2

Putting x and k in (i)

y = $\frac{28}{2}$

y = 14