Đáp án:
Giải thích các bước giải:
a,5-2x=7-x
⇔5-2x-7+x=0
⇔-2-x=0
⇔x=-2
b,2x+13=x+7
⇔2x-x+13-7=0
⇔x+6=0
⇔x=-6
c,2|5-x|=10
⇔|5-x|=5
⇔\(\left[ \begin{array}{l}5-x=5\\5-x=-5\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=10\end{array} \right.\)
d, |x+3|=3
⇔\(\left[ \begin{array}{l}x+3=-3\\x+3=3\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=-6\\x=0\end{array} \right.\)
e,x+1:x+5
⇔{(x+5)-4}:(x+5)
mà x+5:x+5
⇒4:(x+5)
⇒\(\left[ \begin{array}{l}x+5=4\\x+5=-4\end{array} \right.\)
\(\left[ \begin{array}{l}x+5=2\\x+5=-2\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=-1\\x=-9\end{array} \right.\)
\(\left[ \begin{array}{l}x=-3\\x=-7\end{array} \right.\)
g,2x+7:x-2
⇔(2x-4)+11:(x-2)
mà 2x-4:x-2
⇒11:x-2
⇒\(\left[ \begin{array}{l}x-2=11\\x-2=-11\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=13\\x=-9\end{array} \right.\)
h,4-x:x+1
⇔-(x+1)+5:(x+1)
mà -(x+1):(x+1)
⇒5:(x+1)
⇒\(\left[ \begin{array}{l}x+1=5\\x+1=-5\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=4\\x=-6\end{array} \right.\)
