Question

1) tìm x biết : 

\(\left|x+1\right|+2x=-2\)

Answer 1

\(\left|x+1\right|+2x=-2\)

\(\Rightarrow\left|x+1\right|=-2-2x\)

\(\Rightarrow x+1=\pm\left(-2-2x\right)\)

+) \(x+1=-2-2x\)

\(\Rightarrow x+2x=-2-1\)

\(\Rightarrow3x=-3\)

\(\Rightarrow x=-1\)

+) \(x+1=-\left(-2-2x\right)\)

\(x+1=2+2x\)

\(\Rightarrow x-2x=2-1\)

\(\Rightarrow-x=1\)

\(\Rightarrow x=-1\)

Vậy \(x=-1\)

\(\)

Answer 2

|x + 1| + 2x = -2

+ Với x < -1 thì |x + 1| = -(x + 1) = -x - 1

Ta có: -x - 1 + 2x = -2

=> x - 1 = -2

=> x = -2 + 1

=> x = -1, thỏa mãn x < -1

+ Với \(x\ge-1\) thì |x + 1| = x + 1

Ta có: x + 1 + 2x = -2

=> 3x = -2 - 1

=> 3x = -3

=> x = -3 : 3

=> x = -1, thỏa mãn \(x\ge-1\)

Vậy x = -1