Đáp án:
`a) 2/5x+3/7=-4/5`
`-> 2/5x=-4/5-3/7`
`-> 2/5x=-43/35`
`-> x=(-43)/35:2/5`
`-> x=-43/14`
`b) 4/5-(x-1/2)=(-1+1/2)^2`
`-> 4/5-x+1/2=1/4`
`-> 13/10-x=1/4`
`-> x=13/10-1/4`
`-> x=21/20`
`c) 2 2/3:x=1 7/9:0,02`
`-> 8/3:x=800/9`
`-> x=8/3:800/9`
`-> x=3/100`
`d) |x+3/4|-1/3=0`
`-> |x+3/4|=1/3`
`->` \(\left[ \begin{array}{l}x+\dfrac{3}{4}=\dfrac{1}{3}\\x+\dfrac{3}{4}=-\dfrac{1}{3}\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=-\dfrac{5}{12}\\x=-\dfrac{13}{12}\end{array} \right.\)
