EduNinja

IGCSE Math B1.E Rationalising denominatorsTopic Practice

1.E Rationalising denominators

Rationalising the denominator 15 72−

Question 15

Without using a calculator and showing all your working, express
4124+12\frac{4-\sqrt{12}}{4+\sqrt{12}}
in the form aba-\sqrt b where a and b are integers.

Question 15

Without using a calculator and showing all your working, express
11+2321\frac{11+\sqrt2}{3\sqrt2-1}
in the form a+b2a+b\sqrt2, where a and b are integers.

Question 17

Without using a calculator and showing all your working, express
4233+1\frac{4-2\sqrt3}{\sqrt3+1}
in the form a3+ba\sqrt3+b, where a and b are integers.

Question 17

Without using a calculator and showing all your working, express
4+2737\frac{4+2\sqrt7}{3-\sqrt7}
in the form a+ba+\sqrt b, where a and b are integers.

Question 18

Given that
p=1+52,p=\frac{1+\sqrt5}{2},
show that
1p=p1.\frac1p=p-1.
Show your working clearly.

Question 20

Question image

Diagram NOT accurately drawn.

The diagram shows rectangle ABCD.
AD=BC=(22) cmAD=BC=(2-\sqrt2)\text{ cm}Area of ABCD=3(522) cm2.\text{Area of }ABCD=3(5\sqrt2-2)\text{ cm}^2.
Show that the length of AB can be written in the form (a+b2)(a+b\sqrt2) cm, where a and b are integers to be found.
Show your working clearly.

Question 20

Without using a calculator, show that
(27+3)245+3\frac{(\sqrt{27}+\sqrt3)^2}{\sqrt{45}+3}
can be written in the form abaa\sqrt b-a, where a and b are integers.
Show your working clearly.

Question 27(b)

[Maximum number: 2]

Answer parts (a) and (b).

Without using your calculator and showing all your working, express
6+23328\frac{6+2\sqrt3}{3\sqrt2-\sqrt8}
in the form p+q\sqrt p+\sqrt q, where p and q are integers.

0 selected