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Expand following, using suitable identities :-`[1/4a-1/2b+1]^2`

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#### Solution

It is known that,

(x + y + z)^{2} = x^{2} + y^{2} + z^{2} + 2xy + 2yz + 2zx

`[1/4a-1/2b+1]^2 = (1/4a)^2 + (-1/2b)^2 + (1)^2 + 2(1/4a)(-1/2b) + 2(-1/2b)(1) + 2(1)(1/4a)`

`= 1/16a^2 + 1/4b^2 + 1 - 1/4ab - b + 1/2a`

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