Question

explain question 1 please fast

Answer 1

Given question

(3 - √7)(3 + √7)

We have to find whether it is rational or irrational.


First of all if you carefully see the question you will find that this is in the form of

(a + b)(a - b)

We know that, (a + b)(a - b) = a² - b²

So,

(3 - √7)(3 + √7)

= (3)² - (√7)²

=> 9 - 7

= 2

Since the product of (3 - √7)(3 + √7) is 2, which is a rational number, we can say that

(3 - √7)(3 + √7) is also a rational number.


Hope it helps dear friend ☺️✌️

Answer 2

HEY MATE HERE IS YOUR ANSWER

$(3 - \sqrt{7} )(3 + \sqrt{7} )$
To find : wether it is rational or irrational

Now,

Using identity

$(a + b)(a - b) = {a}^{2} - {b}^{2}$
Put values

$(3 - \sqrt{7} )( 3 + \sqrt{7} ) = ({3})^{2} - { \sqrt{(7)} }^{2}$
Square of 3 is 9

Square of root 7 is 7

So,

➡️ 9 - 7

➡️ 2 ( 2 is rational)

Therefore,

(3 - root 7)(3 + root 7) is rational

___________________

Hope it will help you