Question

Tính một cách hợp lí:

a) \(\left(\dfrac{617}{191}+\dfrac{29}{33}-\dfrac{115}{117}\right).\left(\dfrac{1}{4}-\dfrac{1}{5}-\dfrac{1}{20}\right);\)

b) \(\dfrac{12}{5}\cdot\left(\dfrac{10}{3}-\dfrac{5}{12}\right);\)

c) 1,23 - 5,48 + 8,77 - 4,32;

d) 7.0,25 + 9.0,25.

Answer 1

a) Ta có: \(\left(\dfrac{617}{191}+\dfrac{29}{33}-\dfrac{115}{17}\right)\cdot\left(\dfrac{1}{4}-\dfrac{1}{5}-\dfrac{1}{20}\right)\)

\(=\left(\dfrac{617}{191}+\dfrac{29}{33}-\dfrac{115}{17}\right)\cdot\left(\dfrac{5}{20}-\dfrac{4}{20}-\dfrac{1}{20}\right)\)

\(=0\cdot\left(\dfrac{617}{191}+\dfrac{29}{33}-\dfrac{115}{17}\right)=0\)

Answer 2

b) Ta có: \(\dfrac{12}{5}\cdot\left(\dfrac{10}{3}-\dfrac{5}{12}\right)\)

\(=\dfrac{12}{5}\cdot\left(\dfrac{40}{12}-\dfrac{5}{12}\right)\)

\(=\dfrac{12}{5}\cdot\dfrac{35}{12}\)

=7

Answer 3

c) Ta có: \(1.23-5.48+8.77-4.32\)

\(=\left(1.23+8.77\right)-\left(5.48+4.32\right)\)

=10-10=0

Answer 4

d) Ta có: \(7\cdot0.25+9\cdot0.25\)

\(=0.25\left(7+9\right)\)

\(=0.25\cdot16=4\)