Question

Steps to rationalise the denominator1/5-2√5

Answer 1

=1/5-2√5
Multiply and divide by 5+2√5

= 5+2√5/(5-2√5)(5+2√5)

= 5+2√5/(25-20)

=(5+2√5)/5

Answer 2

Hello friends!!

Here is your answer :

$\frac{1}{5 - 2 \sqrt{5} }$


$= \frac{1}{5 - 2 \sqrt{5} } \times \frac{5 + 2 \sqrt{5} }{5 + 2 \sqrt{5} }$


$= \frac{1(5 + 2 \sqrt{5}) }{(5 - 2 \sqrt{5} )(5 + 2 \sqrt{5} )}$


Using identity :

( a + b) ( a - b) = a² - b²


$= \frac{5 + 2 \sqrt{5} }{ {(5)}^{2} - {(2 \sqrt{5}) }^{2} }$



$= \frac{5 + 2 \sqrt{5} }{25 - 20}$


$= \frac{5 + 2 \sqrt{5} }{5}$



Hope it helps you...