Question

Plz give the answers of 10th and 13th.......

Answer 1

steps to the sum no. 10
first take out the squares in bracket
then multiply 1996*994
then the add squares of 998+994
then subtract the sum of 998 and 994 with product of 1996 and 994 . u will get the correct answer. I did not this sum from BODMAS rule. hope it helps you Pls mark me brain list

Answer 2

(10).

Given : (998)^2 + (994)^2 - 1996 * 994

It can be written as:

⇒ (998)^2 + (994)^2 - 2(998)(994)

It is in the form of a^2 + b^2 - 2ab = (a - b)^2

⇒ (998 - 994)^2.

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(13).

Given : x = 3 + √8.

On squaring both sides, we get

⇒ x^2 = (3 + √8)^2

⇒ x^2 = 9 + 8 + 6√8.

⇒ x^2 = 17 + 6√8

Then,

$= > \frac{1}{x^2} = \frac{1}{17 + 6\sqrt{8}} * \frac{17 - 6\sqrt{8}}{17 - 6\sqrt{8} }$

$= > \frac{17 - 6\sqrt{8}}{(17)^2 - (6\sqrt{8})^2}$

$= > \frac{17 - 6\sqrt{8}}{289 - 288}$

$= > 17 - 6\sqrt{8}$

Hence,

⇒ x^2 + 1/x^2

⇒ (17 + 6√8 + 17 - 6√8)

⇒ 17 + 17

⇒ 34.

Therefore, x^2 + 1/x^2 = 34.

Hope it helps!