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Factorise: a.(y + 4)^3 b.(4y – 2)^3c.(y – 6)^3 d.(6y + 1)^3 |
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Answer» Answer: a.(y + 4)^3 = y^3+4^3+3(y)(4)(y+4) = y^3+64+12y(y+4) = y^3+64+12y^2+48y = y^3+12y^2+48y+64 b.(4y – 2)^3 = (4y)^3-(2)^3-3(4y)(2)(4y-2) = 64y^3-8-24y(4y-2) = 64y^3-8-96y^2+48y = 64y^3-96y^2+48y-8 c.(y – 6)^3 = y^3-6^3-3(y)(6)(y-6) =y^3-216-18y(y-6) = y^3-216-18y^2+108y =y^3-18y^2+108y-216 d.(6y + 1)^3 = (6y)^3+1^3+3(6y)(1)(6y+1) = 216y^3+1+18y(6y+1) = 216y^3+1+108y^2+18y = 216y^3+108y^2+18y+1 |
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