Đáp án: Tìm số nguyên x , biết a)3(x-4)-2(x+3)=-18 b)-5(3-x)-4(x+8)=19 c)-12(x-5)+7(3-x)=5 d)30(x+2)-6(x-5)-24x=100 - a) 3(x-4)-2(x+3)=-18 ⇒3x-12-2x-6=-18 ⇒x−18=−18 ⇒x=-18+18 ⇒x=0 (Vậy x = 0) _______________________________________ b) -5(3-x)-4(x+8)=19 ⇒−15+5x−4x−32=19 ⇒-47+x=19 ⇒x-47=19 ⇒x=19+47 ⇒x=66 Vậy x=66 _______________________________________ c) -12(x-5)+7(3-x)=5 ⇒-19x+81=5 ⇒-19x=5-81 ⇒-19x=-76 ⇒x=-76-19 ⇒x...

a) 3(x-4)-2(x+3)=-18 ⇒3x-12-2x-6=-18 ⇒x−18=−18 ⇒x=-18+18 ⇒x=0 (Vậy x = 0) _______________________________________ b) -5(3-x)-4(x+8)=19 ⇒−15+5x−4x−32=19 ⇒-47+x=19 ⇒x-47=19 ⇒x=19+47 ⇒x=66 Vậy x=66 _______________________________________ c) -12(x-5)+7(3-x)=5 ⇒-19x+81=5 ⇒-19x=5-81 ⇒-19x=-76 ⇒x=-76-19 ⇒x...

#andy [(l)a)3( (x - 4) ) - 2( (x + 3) ) = - 18 ⇔ 3x - 12 - 2x - 6 = - 18 ⇔ 3x - 2x = - 18 + 12 + 6 ⇔ x = 0Vậy x = 0b) - 5( (3 - x) ) - 4( (x + 8) ) = 19 ⇔ - 15 + 5x - 4x - 32 = 19 ⇔ 5x - 4x = 19 + 15 + 32 ⇔ x = 66Vậy x = 66c) - 12( (x - 5) ) + 7( (3 - x) ) = 5 ⇔ - 12x + 60 + 21 - 7x = 5 ⇔ - 12x - 7x = 5 - 60 - 21 ⇔ - 19x = - 76 ⇔ x = 4Vậy x = 4d)30( (x + 2) ) - 6( (x - 5) ) - 24 x = 100 ⇔ 30x + 60 - 6x + 30 - 24x = 100 ⇔ 30x - 6x - 24x = 100 - 60 - 30 ⇔ 0x = 10 ( (vô lý) ) ⇒ ∅ ]

windown143

6 tháng trước

Tìm số nguyên x , biết: a)3.(x-4)-2.(x+3)=-18 b)-5.(3-x)-4.(x+8)=19 c)-12.(x-5)+7.(3-x)=5 d)30.(x+2)-6.(x-5)-24.x=100

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baonhivu1234

6 tháng trước

$a)$ $3.\left(x-4\right)-2.\left(x+3\right)=-18$

$⇒3x-12-2x-6=-18$

$⇒x−18=−18$

$⇒x=-18+18$

$⇒x=0$

$\text{Vậy x = 0}$

_______________________________________

$b)$ $-5.\left(3-x\right)-4.\left(x+8\right)=19$

$⇒−15+5x−4x−32=19$

$⇒-47+x=19$

$⇒x-47=19$

$⇒x=19+47$

$⇒x=66$

`Vậy` $x=66$

_______________________________________

$c)$ $-12\left(x-5\right)+7\left(3-x\right)=5$

$⇒-19x+81=5$

$⇒-19x=5-81$

$⇒-19x=-76$

$⇒x=-76:-19$

$⇒x=4$

`Vậy` $x=4$

_______________________________________

$d)$ $30. \left(x+2\right)-6. \left(x-5\right)-24.\:x=100$

$⇒30x+60-6x+30-24x=100$

$⇒60+30=100$

$⇒90=100$

$\text{Vậy không có giá trị x nào.}$

andybao2007

6 tháng trước

#andy

\[\begin{array}{l}
a)3.\left( {x - 4} \right) - 2.\left( {x + 3} \right) = - 18\\
\Leftrightarrow 3x - 12 - 2x - 6 = - 18\\
\Leftrightarrow 3x - 2x = - 18 + 12 + 6\\
\Leftrightarrow x = 0\\
Vậy\,\,x = 0\\
b) - 5.\left( {3 - x} \right) - 4.\left( {x + 8} \right) = 19\\
\Leftrightarrow - 15 + 5x - 4x - 32 = 19\\
\Leftrightarrow 5x - 4x = 19 + 15 + 32\\
\Leftrightarrow x = 66\\
Vậy\,\,x = 66\\
c) - 12\left( {x - 5} \right) + 7\left( {3 - x} \right) = 5\\
\Leftrightarrow - 12x + 60 + 21 - 7x = 5\\
\Leftrightarrow - 12x - 7x = 5 - 60 - 21\\
\Leftrightarrow - 19x = - 76\\
\Leftrightarrow x = 4\\
Vậy\,\,x = 4\\
d)30.\left( {x + 2} \right) - 6.\left( {x - 5} \right) - 24.\,x = 100\\
\Leftrightarrow 30x + 60 - 6x + 30 - 24x = 100\\
\Leftrightarrow 30x - 6x - 24x = 100 - 60 - 30\\
\Leftrightarrow 0x = 10\,\,\left( {vô\,\,lý} \right)\\
\Rightarrow \emptyset
\end{array}\]