Question

Rút gọn biểu thức :

a)A = |x| + x

b)B=|x|-x

c)C=3(x-1)-2|x-3|

 

Answer 1

a)A = |x| + x=x+x=2x

b)B=|x|-x=x-x=0

Answer 2

a) TH1: x < 0 ; ta có:

\(A=\left|x\right|+x=\left(-x\right)+x=0\)

TH2: \(x\ge0\); ta có:

\(A=\left|x\right|+x=x+x=2x\)

b)TH1: x < 0 ; ta có:

\(B=\left|x\right|-x=\left(-x\right)-x=-2x\)

TH2: \(x\ge0\); ta có:

\(B=\left|x\right|-x=x-x=0\)

c) TH1: x < 3 ; ta có:

\(C=3\left(x-1\right)-2\left|x-3\right|=3x-3-2\left(3-x\right)\)

\(=3x-3-6+2x=5x-9\)

TH2: \(x\ge3\); ta có:

\(C=3x-3-2\left(x-3\right)=3x-3-2x+6=x+3\)