Question

Given $\sqrt{5}=2.236$ the value of $\sqrt{45}+\sqrt{605}-\sqrt{245}$ correct to $3$ decimal places is

• A. $15.652$
• B. $11.180$
• C. $18.652$
• D. $16.652$

Answer 1

The correct option is A $15.652$

$\sqrt{45}+\sqrt{605}-\sqrt{245}$
$\Rightarrow \sqrt{9\times 5}+\sqrt{121\times 5}-\sqrt{49\times 5}$
$\Rightarrow 3\sqrt{5}+11\sqrt{5}-7\sqrt{5}$
Given $\sqrt{5}=2.236$
$\Rightarrow 3\times 2.236+11\times 2.236-7\times 2.236$
$\Rightarrow 6.708+24.596-15.652$
$\Rightarrow 31.304-15.652$
$\Rightarrow 15.652$