Question

Which expression is equal to 728‾‾‾√−563‾‾‾√ ?

Answer 1

The answer is The 3rd one

Answer 2

Answer:

The correct option is 3.

Step-by-step explanation:

The given expression is

$7\sqrt{28}-5\sqrt{63}$

It can be written as

$7\sqrt{4\times 7}-5\sqrt{9\times 7}$

$7\sqrt{2^2\times 7}-5\sqrt{3^2\times 7}$

Using product property of radical expressions, we get

$7(\sqrt{2^2}\times \sqrt{7})-5(\sqrt{3^2}\times \sqrt{7})$               $[\because \sqrt{ab}=\sqrt{a}\sqrt{b}]$

$7(2\times \sqrt{7})-5(3\times \sqrt{7})$

$14\sqrt{7}-15\sqrt{7}$

Taking out common factors.

$\sqrt{7}(14-15)$

$\sqrt{7}(-1)$

$-\sqrt{7}$

Therefore the correct option is 3.