Đáp án:
`a) A=5.|-1/12|+(5/9-7/12)-(2/3-5/6)^2`
`A=5.1/12-1/36-(-1/6)^2`
`A=5/12-1/36-1/36`
`A=13/26`
`b) |x+1|+2/5=(7/4)/(5/4)+2`
`<=> |x+1|+2/5=7/5+2`
`<=> |x+1|+2/5=17/5`
`<=>|x+1|=17/5-2/5`
`<=> |x+1|=3`
`<=>`\(\left[ \begin{array}{l}x+1=3\\x+1=-3\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2\\x=-4\end{array} \right.\)
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