desprate help on surds?

Question

if anyone knows the mothod of finding the answer to this question i would really apreciate it

4
---

3-/7

its rationalising the denominator

i was doing well up to now

much apriciated

best comment for som1 that tells me the method too!!!

cheers!

Answer 1

To rationalise the denominator, multiply both numerator and denominator by any surds left in the denominator. In this case we multiply both by √7:

4 / (3√7)
= (4 / (3√7)) . (√7 / radic;7)
= (4√7) / (3(√7)^2)
= 4 √ 7 / 21.

Answer 2

4/( 3 - sqrt(7))

multiply with (3 + sqrt(7))/(3 + sqrt(7))

4(3 + sqrt(7))/(3 - sqrt(7))(3 + sqrt(7) =

4(3 + sqrt(7))/(9 - 7) =

4(3 + sqrt(7))/2 =

2(3 + sqrt(7) =

6 + 2 sqrt(7)