SELINA Solution Class 9 Chapter 1 Rational and Irrational Numbers Exercise 1D

Question 1

Simplify : ${\displaystyle \frac{\sqrt{18}}{5\sqrt{18}+3\sqrt{72}-2\sqrt{162}}}$

Sol:

${\displaystyle \frac{\sqrt{18}}{5\sqrt{18}+3\sqrt{72}-2\sqrt{162}}}$

= ${\displaystyle \frac{\sqrt{9\times 2}}{5\sqrt{9\times 2}+3\sqrt{36\times 2}-2\sqrt{81\times 2}}}$

= ${\displaystyle \frac{3\sqrt{2}}{15\sqrt{2}+18\sqrt{2}-18\sqrt{2}}}$

= ${\displaystyle \frac{3\sqrt{2}}{15\sqrt{2}}}$

= ${\displaystyle \frac{1}{5}}$