Đáp án:
Giải thích các bước giải:
c)|2x+3|+x=21
⇔|2x+3|=21-x (x≤21)
⇔\(\left[ \begin{array}{l}2x+3=21-x\\2x+3=x-21\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=6(n)\\x=-24(n)\end{array} \right.\)
vây:S={6;-24}
d)|3x-7|=2x+1 (x$\geq$-0,5)
⇔\(\left[ \begin{array}{l}3x-7=2x+1\\3x-7=-2x-1\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=8(n)\\x=1,2(n)\end{array} \right.\)
vậy:S={8;1,2}
e)|2x-1|+1=x
⇔|2x-1|=x-1 (x$\geq$1)
⇔\(\left[ \begin{array}{l}2x-1=x-1\\2x-1=1-x\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0(l)\\x=\frac{2}{3}(n)\end{array} \right.\)
vậy:S={$\frac{2}{3}$}
