Tìm x (x-3)^3-(x-3).(x^2+3x+9)+9.(x+1)^2=4
Tìm x (x-3)^3-(x-3).(x^2+3x+9)+9.(x+1)^2=4
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Tìm x (x-3)^3-(x-3).(x^2+3x+9)+9.(x+1)^2=4
Helga
Đáp án: `x=\frac{-1}{9}`
Giải thích các bước giải:
$(x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=4$
$⇔(x^3-9x^2+27x-27)-(x^3-27)+9(x^2+2x+1)=4$
$⇔x^3-9x^2+27x-27-x^3+27+9x^2+18x+9=4$
$⇔45x+9=4$
$⇔45x=-5$
`⇔x=\frac{-1}{9}`
Nho
Các bước giải:
`(x -3)³ -(x -3).(x² +3x +9) +9.(x +1)² = 4`
`⇔ x³ -9x² +27x -27 -x³ +27 +9x² +18x +9 -4 = 0`
`⇔ 45x +5 = 0`
`⇔ x = -1/9`
Vậy `S = {-1/9}`