Question

Tìm x biết :\(\left|x-7\right|+2x+5=6\)

Answer 1

với x>0\(\left|x-7\right|=x-7\Rightarrow x-7+2x+5=6\Rightarrow3x=8\Rightarrow x=\dfrac{8}{3}\)

với x<0\(\left|x-7\right|=7-x\Rightarrow7-x+2x+5=6\Rightarrow x=-6\Rightarrow x=6\)

Answer 2

\(\left | x - 7 \right | + 2x + 5 =6\)

\(\left | x - 7 \right | =6 - 5 - 2x\)

\(\left | x - 7 \right | =1 - 2x\)

+ x - 7 = 1 - 2x

x + 2x = 1 + 7

3x = 8

=> x = \(\frac{8}{3}\)

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

x - 7 = - 1 + 2x

x - 2x = - 1 + 7

- x = 6

x = - 6

Vậy x = \(\frac{8}{3}\); x = - 6