Đáp án:
Giải thích các bước giải:
`1`.
a) `3 1/2-1/2-x=2/3`
`=>3+1/2-1/2-x=2/3`
`=>3-x=2/3`
`=>x=7/3`
Vậy `x=7/3`.
b) $3,2x+(-1,2)x+2,7=\!-4,9\\\Rightarrow\dfrac{16}{5}x+\dfrac{-6}{5}x+\dfrac{27}{10}=\dfrac{-49}{10}\\\Rightarrow x.\left(\dfrac{16}{5}+\dfrac{-6}{5}\right)=\dfrac{-38}{5}\\\Rightarrow x.2=\dfrac{-38}{5}\\\Rightarrow x=\dfrac{-19}{5}$
Vậy `x=(-19)/5`.
`2`.
a) `1/3*3/5+4/5*1/3+1/3*8/5`
`=1/3.(3/5+4/5+8/5)`
`=1/3*3`
`=1`
b) $|\!-0,75|+\dfrac{1}{4}-2\dfrac{1}{2}\\=\dfrac{3}{4}+\dfrac{1}{4}-\dfrac{5}{2}\\=1-\dfrac{5}{2}\\=\dfrac{-3}{2}$