Question

What are the identities in factorisation?​

Answer 1

In 8th grade, CBSE, you learn about 4 identities:

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

In 9th grade, CBSE, you learn about 4 more identities:

$(a+b+c)^2 = a^2 + b^2 + c^2 +2ab +2bc +2ac\\\\(a+b)^3 = a^3 +b^3 + 3ab(a+b) = a^3 + b^3 + 3a^2b + 3ab^2\\\\(a+b)^3 = a^3 -b^3 -3ab(a-b) = a^3 -b^3 -3a^2b + 3ab^2\\\\a^3 + b^3 +c^3 - 3abc = (a+b+c)(a^2+b^2+c^2-ab-bc-ac)$

These 8 identities are very important as it used to derive other identities from them such as   $a^4+b^4, a^3+b^3$  and so on, they are also to be used in higher classes.

So be thorough with your basics as you will definitely benefit from them in the future.

Hope it helps.

Have a great day! ;)

Answer 2

These are some basic formulas to be known for foundational maths

Hope it helps you, Bye da