- (x + y)2
= x2 + 2xy + y2
- (x - y)2
= x2 - 2xy + y2
- x2
- y2 = (x + y)(x - y)
- (x + a)(x +
b) = x2 + (a+b)x + ab
- (x + y + z)2
= x2 + y2 + z2 + 2xy + 2yz + 2zx
- (x + y)3
= x3 + y3 + 3xy(x+y)
- (x - y)3
= x3 - y3 - 3xy(x-y)
- x3
+ y3 + z3 - 3xyz =
(x + y + z)( x2 + y2 + z2 - xy - yz –
zx)
|
These are very important identities , one should remember.
ReplyDeleteUnderstanding of these identities are fundamental for factorization of the polynomials.
Needless to say solving enough number of such problems will give confidence.