Question

please help me solve this question of Maths

Answer 1

I apologise for my handwriting. Hope this helps.

Answer 2

Hello User !

Answers are given below :

1)  ( 5 + $\sqrt{7}$ )( 5 - $\sqrt{7}$ )
     
Let us consider 'a' = 5 and 'b' = $\sqrt{7}$ , then this expression can be written as :

(a + b)(a - b) , which is an identity and is equal to a² - b² .

Therefore, 

( 5 + $\sqrt{7}$ )( 5 - $\sqrt{7}$ ) = (5)² - ($\sqrt{7}$)² 

⇒ 25 - 7 = 18 

This is answer of your first question .

Hope this helps !