Question

Answer 1

`6`

`a,(2x+1)(2x-1)`

`=(2x)^2 -1^2`

`= 4x^2-1`

`b,(x+2/3 y)(x-2/3 y)`

`= x^2-(2/3 y)^2`

`=x^2- 4/9 y^2`

`c,(3/2 x +3/5 y)(3/5 y-3/2 x)`

`= ( 3/5 y + 3/2x ) (3/5 y -3/2 x)`

`=(3/5 y)^2 -(3/2 x)^2`

`= 9/25 y^2 - 9/4 x^2`

Answer 2

7:

a: x^2-2xy+y^2=(x-y)^2

b: 4x^2y^2+12xy+9=(2xy+3)^2

9:

a: (a+b-c)^2

=a^2+b^2+c^2+2ab-2ac-2bc+2ab

b: (x+y+z)(x+y-z)

=(x+y)^2-z^2

=x^2+2xy+y^2-z^2