Câu 1. (2 điểm) Tính: a) $\frac{3}{7}$ + $\frac{4}{7}$.$\frac{-3}{4}$ b) $\frac{-5}{17}$.$\frac{4}{13}$ + $\frac{9}{13}$.$\frac{-5}{17}$ c) $\frac{-20}{41}$ + $\frac{4}{37}$ - $\frac{20}{41}$ + $\frac{33}{37}$ + 0,5 d) 3 : (-$\frac{3}{2}$)² + $\frac{1}{9}$.$\sqrt{36}$

Đáp án+Giải thích các bước giải:

 `a)3/7+4/7 . (-3/4)`

`=3/7 + (-3/7)`

`=0`

`b)-5/17 . 4/13 + 9/13 . (-5/17)`

`=(-5/17 ) .(4/13 + 9/13)`

`=(-5/17)  . 13/13`

`=-5/17 . 1`

`=-5/17`

`c)-20/41+4/37-20/41+33/27+0,5`

`=(-20/41-20/41)+(4/37+33/37)+0,5`

`=-40/41+37/37+0,5`

`=-40/41 + 3/2`

`=43/82`

`d)3 : (-3/2)^2+1/9. \sqrt{36}`

`=3 : 9 /4 + 1/9 . 6`

`=4/3 + 2/3`

`=6/3`

`=2`