Question

tìm x biết

a) (2x-7)-(x+135)=0

b) 12-(39-3x)=0

c) (14-3x)+(6+x)=0

Answer 1

a) ta có : \(\left(2x-7\right)-\left(x+135\right)=0\Leftrightarrow2x-7-x-135=0\)

\(\Leftrightarrow x-142=0\Leftrightarrow x=142\) vậy \(x=142\)

b) ta có : \(12-\left(39-3x\right)=0\Leftrightarrow12-39+3x=0\Leftrightarrow3x-27=0\)

\(\Leftrightarrow3x=27\Leftrightarrow x=\dfrac{27}{3}=9\) vậy \(x=9\)

c) ta có : \(\left(14-3x\right)+\left(6+x\right)=0\Leftrightarrow14-3x+6+x=0\)

\(\Leftrightarrow20-2x=0\Leftrightarrow2x=20\Leftrightarrow x=\dfrac{20}{2}=10\) vậy \(x=10\)