Question

please tell the four important identities​

Answer 1

Identity - [i]

$\sf {(x + y)}^{2} = {x}^{2} + 2xy + {y}^{2}$

Identity - [ii]

$\sf {(x - y)}^{2} = {x}^{2} - 2xy + {y}^{2}$

Identity - [iii]

$\sf(x + y)(x - y) = {x}^{2} - {y}^{2}$

Identity - [iv]

$\sf(x + a)(x + b) = {x}^{2} + x(a + b) + ab$

Answer 2

Answer:

Identity - [i]

\sf {(x + y)}^{2} = {x}^{2} + 2xy + {y}^{2}(x+y)

2

=x

2

+2xy+y

2

Identity - [ii]

\sf {(x - y)}^{2} = {x}^{2} - 2xy + {y}^{2}(x−y)

2

=x

2

−2xy+y

2

Identity - [iii]

\sf(x + y)(x - y) = {x}^{2} - {y}^{2}(x+y)(x−y)=x

2

−y

2

Identity - [iv]

\sf(x + a)(x + b) = {x}^{2} + x(a + b) + ab(x+a)(x+b)=x

2

+x(a+b)+ab