1. Expand `(x-6)(x+6)`

Solution:
`"Using the identity,"`

`(X+A)(X-A)=X^2-A^2`

`"Here "X=x,A=-6`

`=(x)^2-(-6)^2`

`=x^2-36`

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2. Expand `(2x-5)(2x+5)`

Solution:
`"Using the identity,"`

`(X+A)(X-A)=X^2-A^2`

`"Here "X=2x,A=-5`

`=(2x)^2-(-5)^2`

`=4x^2-25`

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3. Expand `(3x-2)(3x+2)`

Solution:
`"Using the identity,"`

`(X+A)(X-A)=X^2-A^2`

`"Here "X=3x,A=-2`

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

`=9x^2-4`

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4. Expand `(x-y)(x+y)`

Solution:
`"Using the identity,"`

`(X+A)(X-A)=X^2-A^2`

`"Here "X=x,A=-y`

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

`=x^2-y^2`

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5. Expand `(x-2y)(x+2y)`

Solution:
`"Using the identity,"`

`(X+A)(X-A)=X^2-A^2`

`"Here "X=x,A=-2y`

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

`=x^2-4y^2`

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