Question

Tính bằng cách thuận tiện.

a) 137 × 25 + 137 × 75                        b) \(\left(\dfrac{4}{9}+\dfrac{3}{5}+\dfrac{5}{9}\right)\)                     c) \(\dfrac{5}{6}-\dfrac{2}{3}+\dfrac{2}{5}\)

Answer 1

a) 137 x 25 + 137 x 75

= 137 x (25 + 75)

= 137 x 100

= 13 700 

b) $\left( {\frac{4}{9} + \frac{3}{5}} \right) + \frac{5}{9}$

$ = \left( {\frac{4}{9} + \frac{5}{9}} \right) + \frac{3}{5}$

$ = 1 + \frac{3}{5}$

$ = \frac{8}{5}$

c) $124,46 + 98,31 + 75,54$

= (124,46 + 75,54) + 98,31

= 200 + 98,31

= 298,31