Question

tính bằng cách hợp lí 

a. [77+ 509 ] + [23+215 ] + 91        ;      b. 13.19 + 82 . 13-13

 

Answer 1

a)(77+509)+(23+215)+91=77+509+23+215+91

                                    =(77+23)+(509+91)+215

                                    =100+600+215

                                    =915

b)13.19+82.13-13=13(19+82-1)

                         =13.100=1300

Answer 2

a(77+509)+(23+215)+91                                     b13,19+82,13-13

=586       +  238   + 91                                         = 95,32  - 13

=      824      +   91                                               =82,32

915

Answer 3

a, [77+509]+[23+215]+91

   =77+509+23+215+91

   =(77+23)+(509+91)+215

   =100+600+215

   =700+215

   =915

b,13.19+82.13-13

   =13.(19+82)-13

   =13.101-13

   =1313-13

   1300

chuc ban hoc giỏi

    

Answer 4

a)\(\left(77+509\right)+\left(23+215\right)+91\)

\(=\left(509+91\right)+\left(23+77\right)+215\)

\(=600+100+215\)

\(=700+215\)

\(=915\)

b)\(13.19+82.13-13\)

\(=\left(19+82\right).13-13\)
\(=101.13-13\)

\(=1313-13\)

\(=1300\)