Find the values of each of the following correct to three places of decimals, it being given that
Find the values of each of the following correct to three places of decimals, it being given that
$\sqrt{2}=1.414, \sqrt{3}=1.732, \sqrt{5}=2.236, \sqrt{6}=2.4495, \sqrt{10}=3.162$
(i) $\frac{3-\sqrt{5}}{3+2 \sqrt{5}}$
(ii) $\frac{1+\sqrt{2}}{3-2 \sqrt{2}}$
(i) $\frac{3-\sqrt{5}}{3+2 \sqrt{5}}$
Rationalizing the denominator by multiplying both numerator and denominator with the rationalizing factor
$3-2 \sqrt{5}$
$=\frac{(3-\sqrt{5})(3-2 \sqrt{5})}{(3+2 \sqrt{5})(3+2 \sqrt{5})}$
Since, $(a+b)(a-b)=\left(a^{2}-b^{2}\right)$
$=\frac{(3-\sqrt{5})(3-2 \sqrt{5})}{9-20}$
$=\frac{(9-6 \sqrt{5}-3 \sqrt{5}+10)}{-11}$
$=\frac{(19-9 \sqrt{5})}{-11}$
$=\frac{(9 \sqrt{5}-19)}{11}$
$=\frac{(9(2.236)-19)}{11}$
$=\frac{(20.124-19)}{11}$
$=\frac{1.124}{11}$
$=0.102$
(ii) $\frac{1+\sqrt{2}}{3-2 \sqrt{2}}$
Rationalizing the denominator by multiplying both numerator and denominator with the rationalizing factor
$3+2 \sqrt{2}$
$=\frac{(1+\sqrt{2})(3+2 \sqrt{2})}{(3-2 \sqrt{2})(3+2 \sqrt{2})}$
As we know, $(a+b)(a-b)=\left(a^{2}-b^{2}\right)$
$=\frac{(1+\sqrt{2})(3+2 \sqrt{2})}{9-8}$
$=3+2 \sqrt{2}+3 \sqrt{2}+4$
$=7+5 \sqrt{2}$
$=7+7.07=14.07$