Question

Tìm x : 

a.12 + x + (-5) = -18 - 2x

b.(-14) - x + (-15) = -10 + (4 - 2x)

c.x - (-19) - (-11) = -(3x + 40)
 

Answer 1

a) \(12+x+\left(-5\right)=-18-2x\)

\(\Rightarrow12+x-5=-18-2x\)

\(\Rightarrow x+7+18+2x=0\)

\(\Rightarrow3x=-25\)

\(\Rightarrow x=-\dfrac{25}{3}\) 

b) \(\left(-14\right)-x+\left(-15\right)=-10+\left(4-2x\right)\)

\(\Rightarrow-14-x-15=-10+4-2x\)

\(\Rightarrow-x-29=-2x-6\)

\(\Rightarrow-x+2x=-6+29\)

\(\Rightarrow x=23\)

c) \(x-\left(-19\right)-\left(-11\right)=-\left(3x+40\right)\)

\(\Rightarrow x+19+11=-3x-40\)

\(\Rightarrow x+30=-3x-40\)

\(\Rightarrow x+3x=-40-30\)

\(\Rightarrow4x=-70\)

\(\Rightarrow x=-\dfrac{35}{2}\)

Answer 2