(x-1)(x^2+x+1) – x(x+2)(x-2)=5 (x-3)^3 – (x-3)(x^2+3x+9) + 9(x+1)^2= 15 x(x-5)(x+5) – (x-2)(x^2+2x+4) = 3 17/08/2021 Bởi Hadley (x-1)(x^2+x+1) – x(x+2)(x-2)=5 (x-3)^3 – (x-3)(x^2+3x+9) + 9(x+1)^2= 15 x(x-5)(x+5) – (x-2)(x^2+2x+4) = 3
`a,(x-1)(x^2+x+1)-x(x+2)(x-2)=5` `⇔x^3-1-x(x^2-4)=5` `⇔x^3-1-x^3+4x=5` `⇔4x=6` `⇔x=3/2` `b,(x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=15` `⇔x^3-9x^2+27x-27-x^3+27+9(x^2+2x+1)=15` `⇔x^3-9x^2+27x-27-x^3+27+9x^2+18x+9=15` `⇔45x=6` `⇔x=2/15` `c,x(x-5)(x+5)-(x-2)(x^2+2x+4)=3` `⇔x(x^2-25)-x^3+8=3` `⇔x^3-25x-x^3+8=3` `⇔-25x=-5` `⇔x=1/5` Bình luận
`a,(x-1)(x^2+x+1)-x(x+2)(x-2)=5`
`⇔x^3-1-x(x^2-4)=5`
`⇔x^3-1-x^3+4x=5`
`⇔4x=6`
`⇔x=3/2`
`b,(x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=15`
`⇔x^3-9x^2+27x-27-x^3+27+9(x^2+2x+1)=15`
`⇔x^3-9x^2+27x-27-x^3+27+9x^2+18x+9=15`
`⇔45x=6`
`⇔x=2/15`
`c,x(x-5)(x+5)-(x-2)(x^2+2x+4)=3`
`⇔x(x^2-25)-x^3+8=3`
`⇔x^3-25x-x^3+8=3`
`⇔-25x=-5`
`⇔x=1/5`
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