Đáp án:
Giải thích các bước giải:
a)(2x+7)+135=0
⇒2x+7=-135
⇒2x =-142
⇒x =-71
b)$\frac{1}{2}$x -$\frac{2}{5}$ =$\frac{1}{5}$
⇒$\frac{1}{2}$x =$\frac{3}{5}$
⇒x =$\frac{6}{5}$
c)|x+1|=5
⇒ \(\left[ \begin{array}{l}x+1=5với x≥-1\\x+1=-5với x<-1\end{array} \right.\)
⇒ \(\left[ \begin{array}{l}x =4(TM)\\x=-6 (TM)\end{array} \right.\)
d)(3 $\frac{1}{2}$+2x).2$\frac{2}{3}$=5$\frac{1}{3}$
⇒($\frac{7}{2}$ +2x) .$\frac{8}{3}$ =$\frac{16}{3}$
⇒$\frac{7}{2}$ +2x =2
⇒2x =$\frac{-3}{2}$
⇒ x =$\frac{-3}{4}$
e)|2x+3|=5
⇒ \(\left[ \begin{array}{l}2x+3=5với x≥\frac{-3}{2} \\2x+3=-5với x<\frac{-3}{2} \end{array} \right.\)
⇒\(\left[ \begin{array}{l}2x=2\\2x=-8\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x =1(TM)\\x=-4(TM)\end{array} \right.\)
f)$\frac{x-2}{4}$ =$\frac{5+x}{3}$
⇒3.(x-2)=4.(x+5)
⇒3x -6 =4x +20
⇒4x-3x =-6-20
⇒x =-26
