Question

1) |7 - x | = 5x + 1

2) |x - 1 | = 3x + 2

3) |x + 15 | + 1 = 3x

4) |x + 7 | -x = 7

Answer 1

1) <=>\(\left[\begin{array}{nghiempt}7-x=5x+1\\7-x=-5x-1\end{array}\right.\)

<=> \(\left[\begin{array}{nghiempt}x=\frac{4}{3}\\x=-2\end{array}\right.\)

2)<=>\(\left[\begin{array}{nghiempt}x+1=3x+2\\x+1=-3x-2\end{array}\right.\)

<=> \(\left[\begin{array}{nghiempt}x=-\frac{3}{2}\\x=-\frac{1}{4}\end{array}\right.\)

 

Answer 2

3)<=> \(\left[\begin{array}{nghiempt}x+15=3x-1\\x+15=1-3x\end{array}\right.\)

<=>\(\left[\begin{array}{nghiempt}x=8\\x=-\frac{7}{2}\end{array}\right.\)

4) \(\left[\begin{array}{nghiempt}x+7=x+7\\x+7=-x-7\end{array}\right.\)=> \(\left[\begin{array}{nghiempt}x\in R\\x=0\end{array}\right.\)

=> S=R