Question

Tìm x:

a) 5 - 4 (x - 2) = 3 . (2 -x)

b) 2 - 3 (x + 1) = x - 7

Answer 1

a)

\(5-4\left(x-2\right)=3\left(2-x\right)\)

\(\Rightarrow\left(-1\right)\left[5-4\left(x-2\right)\right]=3\left(-1\right)\left(2-x\right)\)

\(\Rightarrow4\left(x-2\right)-5=3\left(x-2\right)\)

\(\Rightarrow4\left(x-2\right)-3\left(x-2\right)=5\)

\(\Rightarrow x-2=5\)

\(\Rightarrow x=7\)

Vậy x = 7

b)

\(2-3\left(x+1\right)=x-7\)

\(\Rightarrow2-3x-3=x-7\)

\(\Rightarrow-1-3x=x-7\)

\(\Rightarrow3x+x=7-1\)

\(\Rightarrow4x=6\)

\(\Rightarrow x=\frac{3}{2}\)

Vậy x = 3 / 2