a)3-2(5-x)(x-5)-2(5+x)²
б)(x-y-z)(x-y-z)-(x-y)²
в)(x+y+z)(x-y-z)-(x+y-z)(x-y+z)
г)(x+y-x)(x-y+z)-(x+y+z)(x-y-z)

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