Question

Write the rationalising factor for $7\sqrt{y}$

Answer 1

We know that If the product of two surds is a rational number, then each factor is a rationalising factor of the other.

Now multiply $\sqrt{y}$ to $7\sqrt{y}$ to make $\sqrt{y}$ a rational number as shown below:

$\left(\sqrt{y}\right)\times \left(7\sqrt{y}\right)=7y$

Hence, $\sqrt{y}$ is the rationalising factor of $7\sqrt{y}$.