Question

Y is inversly proportional to x^3 y=28 when x=a work out the value of y when x=2a

Answer 1

y = 7/2

Explanation:

The above statement is written as

`y = \frac{k}{ {x}^(3) }`

where k is constant of variation

y = 28 x = a

`28 = \frac{k}{ {a}^(3) } \\ \\ k = 28 {a}^(3)`

The formula for the variation is

`y = \frac{28 {a}^(3) }{ {x}^(3) }`

when x = 2a

y is

`y = \frac{28 {a}^(3) }{( {2a)}^(3) } \\ y = \frac{ {28a}^(3) }{ {8a}^(3) } \\ \\ y = (28)/(8) \\ \\ y = (7)/(2)`

Hope this helps you