Question

pls can u answer this question 8 th std maths​

Answer 1

Answer: The number is 10.

Step-by-step explanation:

Let the number be x.

$x^{2} + 15 =(x+1)^{2} -6\\x^{2} =x^{2} +1 +2x -6 -15\\x^{2} -x^{2} =2x-21+1\\-2x=-20\\x=-20/-2\\x=10$

Answer 2

Answer:

Step-by-step explanation:

ANSWER:-

• 15 is added to square of a number
• It is equal to 6 less than square of it's successor.
• We need to find the number.

According to Question:-

$15+x^2 = (x+1)^2-6$

Concept used:-

$(a+b)^2 = a^2+b^2+2ab$

Let's solve!

$15+x^2 = x^2+1+2x-6$

$15+6+x^2-x^2-1-2x=0$

(Brought all to one side):-

$-2x+20=0$

$-2x = -20$

$x = 10$ is the answer.

More Identities:-

$(a-b)^2 = a^2+b^2-2ab$

$(a^2-b^2) = (a-b)(a+b)$

$(a^2+b^2) = (a+b)^2-2ab$

$(a^2+b^2) = (a-b)^2+2ab$

• These identities are used to solve these question.
• These are called algebraic Identities.