Question

Tính bằng cách thuận tiện nhất:

a) \(\dfrac{7}{11}+\dfrac{3}{4}+\dfrac{4}{11}+\dfrac{1}{4}\);                                    b) \(\dfrac{72}{99}-\dfrac{28}{99}-\dfrac{14}{99}\);

c) \(69,78+35,97+30,22\);                              d) \(83,45-30,98-42,47\)

Answer 1

a) \(\dfrac{7}{11}+\dfrac{3}{4}+\dfrac{4}{11}+\dfrac{1}{4}=\left(\dfrac{7}{11}+\dfrac{4}{11}\right)+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=1+1=2\)

Answer 2

b) \(\dfrac{72}{99}-\dfrac{28}{99}-\dfrac{14}{99}=\dfrac{72-28-14}{99}=\dfrac{30}{99}=\dfrac{10}{33}\)

Answer 3

c) \(69.78+35.97+30.22=\left(69.78+30.22\right)+35.97=100+35.97=135.97\)

Answer 4

d) \(83.45-30.98-42.47=83.45-73.45=10\)