Tính giá trị các biểu thức sau :
\(A=a.\dfrac{1}{2}+a.\dfrac{1}{3}-a.\dfrac{1}{4}\) với \(a=\dfrac{-4}{5}\)
\(B=\dfrac{3}{4}.b+\dfrac{4}{3}.b-\dfrac{1}{2}.b\) với \(b=\dfrac{6}{19}\)
\(C=c.\dfrac{3}{4}+c.\dfrac{5}{6}-c.\dfrac{19}{12}\) với \(c=\dfrac{2002}{2003}\)
Áp dụng tính chất phân phối, rồi tính giá trị biểu thức.
Chẳng hạn,![This is the rendered form of the equation. You can not edit this directly. Right click will give you the option to save the image, and in most browsers you can drag the image onto your desktop or another program.](http://latex.codecogs.com/gif.latex?A%3Da.%5Cleft%20%28%5Cfrac%7B1%7D%7B2%7D+%5Cfrac%7B1%7D%7B3%7D-%5Cfrac%7B1%7D%7B4%7D%20%5Cright%20%29%3Da.%5Cfrac%7B6+4-3%7D%7B12%7D%3Da.%5Cfrac%7B7%7D%7B12%7D.)
Với
, thì ![This is the rendered form of the equation. You can not edit this directly. Right click will give you the option to save the image, and in most browsers you can drag the image onto your desktop or another program.](http://latex.codecogs.com/gif.latex?A%3D%5Cfrac%7B-4%7D%7B5%7D.%5Cfrac%7B7%7D%7B12%7D%3D%5Cfrac%7B-7%7D%7B15%7D.)
ĐS.
; C = 0.
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