Question

whole identity of polynomial

Answer 1

Polynomial Identities

When we have a sum(difference) of two or three numbers to power of 2 or 3 and we need to remove the brackets we use
polynomial identities(short multiplication formulas):

(x + y)2 = x2 + 2xy + y2
(x - y)2 = x2 - 2xy + y2

Example 1: If x = 10, y = 5a
(10 + 5a)2 = 102 + 2·10·5a + (5a)2 = 100 + 100a + 25a2

Answer 2

(x + y) 2 = x2+ y2 + 2xy