Write the rationalisation factor of `7-3sqrt(5)`

Explanation

`(7- 3√5)` is already in simplest form.

`= (7 - 3√5)( 7+ 3√5)`
Use the algebraic identity `a2 - b2 = (a + b)(a - b)`.
`= (7)^2- (3√5)^2`
`= (7)^2- (3)^2\(√5)^2`
` = 49 - 9(5)`
`= 49 - 45`

`= 4`
`4` is a rational number.
So, the rationalizing factor of `(7 - 3√5)` is `(7 + 3√5)`.