Đáp án+Giải thích các bước giải:
`1)3/8-4/5-(-17)/(40)`
`=3/8-4/5+(17)/(40)`
`=(15)/(40)-(32)/(40)+(17)/(40)`
`=0/(40)`
`=0`
`2)-4/7+2/3 . -9/(14)`
`=-4/7+(-3/7)`
`=-7/7`
`=-1`
`3)(11)/8 . 7/(17)+(11)/(17). ((-15)/(16))-(11)/7`
`=(11)/8 . 7/(17)+[(11)/(17) . ((-15)/(16))-(11)/7]`
`=(11)/8 . 7/(17)+(11)/(17).((-15)/(16) -1)`
`=(11)/8 . 7/(17)+(11)/(17) . (-31)/(16)`
`=(77)/(136)+(-341)/(272)`
`=(-11)/(16)`
`4)(7/(10)-(-3)/4-20%) : (-0,5)^2`
`=(7/(10)+3/4-1/5) : 1/4`
`=((14)/(20)+(15)/(20)-4/(20)) . 4`
`=(25)/(20) .4`
`=5/4 . 4`
`=5`
`5)3 2/7 . 12 1/2 - 3 2/7 . 5 1/2`
`=3 2/7.(12 1/2- 5 1/2)`
`=(23)/7 . ((25)/2-(11)/2)`
`=(23)/7 . (14)/2`
`=(23)/7 .7`
`=23`
`6)3/7(-4/9+5/15)+(5/3-5/9).3/7`
`=3/7.(-4/9+1/3+5/3-5/9)`
`=3/7.[(-4/9-5/9)+(1/3+5/3)]`
`=3/7. ((-9)/9 + 6/3)`
`=3/7.(-1+2)`
`=3/7 . 1`
`=3/7`
`7)(-11)/(12) . (-4)/(33) . (84)/(-25) . (-5)/6`
`=((-11).(-4) . 84 .(-5))/(12 . 33 . (-25) . 6)`
`=((-11) . (-2) . 2 .12 . 7.(-5))/(12. 3 .11.(-5) . 5. 2 .3)`
`=(14)/(45)`
`8)(2 5/(94) -27 +1 (87)/(97)).(1/2-1/3-1/6)`
`=(2 5/(94) -27 +1 (87)/(97)).(3/6-2/6-1/6)`
`=(2 5/(94) -27 +1 (87)/(97)). 0/6`
`=(2 5/(94) -27 +1 (87)/(97)) . 0`
`=0`
`9)(14.25-28)/(7.19+28)`
`=(7(2.25-4))/(7(19+4))`
`=(46)/(23)`
`=2`
`10)7/(12) . 2 1/6 -7/(12). (-5/6)-1`
`=[7/(12) . 2 1/6 - 7/(12) . (-5/6)]-1`
`=7/(12).[2 1/6 - (-5/6)]-1`
`=7/(12).((13)/6+5/6)-1`
`=7/(12). (18)/6 -1`
`=7/(12) . 3 -1`
`=7/4 -1`
`=3/4`