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# C1 Surds watch

1. How do you rationalise the denominator in the case of √15 / √3?
2. Notice that (15)^1/2 = (3*5)^1/2 = (3^1/2)(5^1/2)

Then the 3^1/2 cancel to leave you with just 5^1/2
3. in the answer booklet, it says (√5)/5....
4. √5 is the correct answer. Just remember:

√a / √b = (√a/b)
√15 / √3 = (√15/3) = √5
5. lol, yeah it is √5

√15/√3

multiply both sides by √3:

√15√3/√3√3

simplify:

√45/3

=

√9√5/√3

=

3√5/√3

=

√5

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