A=\(\dfrac{38}{50}\)+\(\dfrac{9}{20}\)-\(\dfrac{11}{30}\)+\(\dfrac{13}{42}\)-\(\dfrac{15}{56}\)+\(\dfrac{17}{72}\)-...+\(\dfrac{197}{9702}\)-\(\dfrac{199}{9900}\)

Tính tổng A= 1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+1/90

tính A=1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90

tính tổng sau :

S=1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90

giúp mình nhanh nha

Tính nhanh:

A=\(\frac{1}{90}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\)

B=\(\frac{3}{2}-\frac{5}{6}+\frac{7}{12}-\frac{9}{20}+\frac{11}{30}-\frac{13}{42}+\frac{15}{56}-\frac{17}{72}\)

Tính:

1 - 5/6 + 7/12 - 9/20 + 11/30 - 13/42 + 15/56 - 17/72 + 19/90

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/91

Tính tổng A= 1- 5/6 +7/12 - 9/20 + 11/30 - 13/42 + 15/56 - 17/72 + 19/90 - 21/110 + 23/132 - 25/156

tinh tong A=1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90