Lời giải:
A=$\dfrac{6}{17}$ + $\dfrac{-8}{25}$ + $\dfrac{-9}{11}$ + $\dfrac{11}{17}$ + $\dfrac{-17}{25}$
A=($\dfrac{6}{17}$ + $\dfrac{11}{17}$) + ($\dfrac{-8}{25}$+$\dfrac{-17}{25}$)+$\dfrac{-9}{11}$
A=$\dfrac{17}{17}$ + $\dfrac{-25}{25}$ + $\dfrac{-9}{11}$
A=1+(-1)+$\dfrac{-9}{11}$
A=0+$\dfrac{-9}{11}$
A=$\dfrac{-9}{11}$
Vậy A=$\dfrac{-9}{11}$
Tính:
a) $\dfrac{1}{6}$ - $\dfrac{1}{2}$
= $\dfrac{2-6}{12}$
= $\dfrac{-4}{12}$
=$\dfrac{-1}{3}$
b) $\dfrac{-3}{4}$ - (-1)
= $\dfrac{1}{4}$
c) $\dfrac{11}{36}$ - $\dfrac{-11}{24}$ (MSC=144)
= $\dfrac{44-(-66)}{144}$
=$\dfrac{110}{144}$
=$\dfrac{55}{72}$
