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`2.`
`a)(3x-1)^2-16`
`=(3x-1)^2-4^2`
`=(3x-1-4)(3x-1+4)`
`=(3x-5)(3x+3)`
______________________
`b)(5x-4)^2-49x^2`
`=(5x-4)^2-(7x)^2`
`=(5x-4-7x)(5x-4+7x)`
`=(-2x-4)(12x-4)`
________________________
`c)9(2x-3)^2-4(x+1)^2`
`=[3(2x-3)]^2-[2(x+1)]^2`
`=[3(2x-3)-2(x+1)][3(2x-3)+2(x+1)]`
`=(6x-9-2x-2)(6x-9+2x+2)`
`=(4x-11)(8x-7)`
_________________________
`d)4b^2c^2-(b^2+c^2-a^2)^2`
`=(2bc)^2-(b^2+c^2-a^2)^2`
`=(2bc-b^2-c^2+a^2)(2bc+b^2+c^2-a^2)`
___________________________
`e)-4x^2+12xy-9y^2+25`
`=-(4x^2-12xy+9y^2-25)`
`=-[(4x^2-12xy+9y^2)-25]`
`=-[(2x-3y)^2-5^2]`
`=-(2x-3y-5)(2x-3y+5)`
______________________________
`f)x^2-2xy+y^2-4m^2+4mn-n^2`
`=(x^2-2xy+y^2)-(4m^2-4mn+n^2)`
`=(x-y)^2-(2m-n)^2`
`=(x-y-2m+n)(x-y+2m-n)`
`color{#dcedc1}{Cow}`
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