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`bb{a})` `(3x-1)^2 -16`
`=(3x-1)^2 -4^2`
`=(3x-1-4)(3x-1+4)`
`=(3x-5)(3x+3)`
`=3(x+1)(3x-5)`
`bb{b})` `(5x-4)^2 -49x^2`
`=(5x-4)^2 -(7x)^2`
`=(5x-4-7x)(5x-4+7x)`
`=(-2x-4)(12x-4)`
`=-2(x+2). 4(3x-1)`
`=-8(x+2)(3x-1)`
`bb{c})` `(2x+5)^2 -(x-9)^2`
`=[(2x+5)-(x-9)][(2x+5)+(x-9)]`
`=(2x+5-x+9)(2x+5+x-9)`
`=(x+14)(3x-4)`
`bb{d})` `(3x+1)^2 -4(x-2)^2`
`=(3x+1)^2 -[2(x-2)]^2`
`=(3x+1)^2 -(2x-4)^2`
`=[(3x+1)-(2x-4)][(3x+1)+(2x-4)]`
`=(3x+1-2x+4)(3x+1+2x-4)`
`=(x+5)(5x-3)`
`bb{e})` `9(2x+3)^2 -4(x+1)^2`
`=[3(2x+3)]^2 -[2(x+1)]^2`
`=(6x+9)^2 -(2x+2)^2`
`=[(6x+9)-(2x+2)][(6x+9)+(2x+2)]`
`=(6x+9-2x-2)(6x+9+2x+2)`
`=(4x+7)(8x+11)`
`bb{f})` `4b^2 c^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)]`
`=(2bc-b^2 -c^2 +a^2)(2bc+b^2 +c^2 -a^2)`
`=[a^2 -(b^2 -2bc+c^2)][-a^2 +(b^2 +2bc+c^2)]`
`=[a^2 -(b-c)^2][(b+c)^2 -a^2]`
`=(a-b+c)(a+b-c)(b+c-a)(b+c+a)`
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