Toán Lớp 8: giải pguongw trình
$\text{( x – 1 ) ³ – x ( x + 1 )² = 5x ( 2 – x ) – 11 ( x + 2 ) }$
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Toán Lớp 8: giải pguongw trình
$\text{( x – 1 ) ³ – x ( x + 1 )² = 5x ( 2 – x ) – 11 ( x + 2 ) }$
Comments ( 2 )
Giải đáp:
S={-7}
Lời giải và giải thích chi tiết:
(x-1)^3-x.(x+1)^2=5x.(2-x)-11.(x+2)
<=>x^3-3.x^2 . 1+3.x.1^2-1^3-x.(x^2+2x+1)=10x-5x^2-11x-22
<=>x^3-3x^2+3x-1-x^3-2x^2-x-10x+5x^2+11x+22=0
<=>(x^3-x^3)+(-3x^2-2x^2+5x^2)+(3x-x-10x+11x)+(-1+22)=0
<=>3x+21=0
<=>3x=-21
<=>x=-7
Vậy S={-7}
( x – 1 ) ^3 – x ( x + 1 )^2 = 5x ( 2 – x ) – 11 ( x + 2 )
<=>x^3-3x^2+3x-1-x(x^2+2x+1)=10x-5x^2-11x-22
<=>x^3-3x^2+3x-1-x^3-2x^2-x=-5x^2-x-22
<=>-5x^2+2x-1=-5x^2-x-22
<=>2x-1=-x-22
<=>3x=-21
<=>x=-7
Vậy x=-7