Toán Lớp 6: Tìm x, biết
a)4(x-1)+5=3(x+2)-26
b) -3(x+5)-(-32)=-2.(x-1)+(-23)
c) 3x+2-2.(x-1)=3x+6
Giúp mik zới mn ơi!!!????????
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Toán Lớp 6: Tìm x, biết
a)4(x-1)+5=3(x+2)-26
b) -3(x+5)-(-32)=-2.(x-1)+(-23)
c) 3x+2-2.(x-1)=3x+6
Giúp mik zới mn ơi!!!????????
Comments ( 2 )
#andy
\[\begin{array}{l}
a)4\left( {x – 1} \right) + 5 = 3\left( {x + 2} \right) – 26\\
\Leftrightarrow 4x – 4 + 5 = 3x + 6 – 26\\
\Leftrightarrow 4x – 3x = 6 – 26 – 5 + 4\\
\Leftrightarrow x = – 21\\
\Leftrightarrow x = – 21\\
b){\rm{ }} – 3\left( {x + 5} \right) – \left( { – 32} \right) = – 2.\left( {x – 1} \right) + \left( { – 23} \right)\\
\Leftrightarrow – 3x – 15 + 32 = – 2x + 2 – 23\\
\Leftrightarrow – 3x + 2x = 2 – 23 – 32 + 15\\
\Leftrightarrow – x = – 38\\
\Leftrightarrow x = 38\\
c){\rm{ }}3x + 2 – 2.\left( {x – 1} \right) = 3x + 6\\
\Leftrightarrow 3x + 2 – 2x + 2 = 3x + 6\\
\Leftrightarrow 3x – 2x – 3x = 6 – 2 – 2\\
\Leftrightarrow – 2x = 2\\
\Leftrightarrow x = – 1
\end{array}\]
Giải đáp:
a)
4(x-1)+5=3(x+2)-26
⇒4.x-4.1+5=3.x+3.2-26
⇒4x+1=3x-20
⇒4x-3x=-20-1
⇒x.(4-3)=-20-1
⇒x=-21
Vậy x=-21
b)
-3.(x+5)-(-32)=-2.(x-1)+(-23)
⇒-3.x-15+32=-2x+2-23
⇒-3x+17=-3x-21
⇒-3x+2x=-21-17
⇒x.(-3+2)=-38
⇒-1.x=-38
⇒x=38
Vậy x=38
c)
3x+2-2.(x-1)=3x+6
⇒3x+2-2x+2=3x+6
⇒3x-2x+1=3x+6
⇒x.(3-2)+1=3x+6
⇒x+4=3x+6
⇒x-3x=6-4
⇒x(1-3)=2
⇒-2.x=2
⇒x=-1
Vậy x=-1