Question

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

−11√ 7
√7
- √7
−37√7

Answer 1

The answer is The 3rd one

Answer 2

The correct option is 3.

Explanation:

The given expression is

`7√(28)-5√(63)`

It can be written as

`7√(4* 7)-5√(9* 7)`

`7√(2^2* 7)-5√(3^2* 7)`

Using product property of radical expressions, we get

`7(√(2^2)* √(7))-5(√(3^2)* √(7))`
`[\because √(ab)=√(a)√(b)]`

`7(2* √(7))-5(3* √(7))`

`14√(7)-15√(7)`

Taking out common factors.

`√(7)(14-15)`

`√(7)(-1)`

`-√(7)`

Therefore the correct option is 3.