Question

Tính bằng cách thuận tiện nhất

2/5+1/6+3/5=

9/13+4/13+2/3=

Answer 1

a, 2/5 + 1/6 + 3/5

= ( 2/5 + 3/5 ) + 1/6

=        5/5 + 1/6

=          1 + 1/6

=         6/6 + 1/6 

=            7/6

b, 9/13 + 4/13 + 2/3

=        13/13    + 2/3

=            1 + 2/3

= 3/3 + 2/3

=             5/3

Answer 2

2/5+1/6+3/5

=(2/5+3/5)+1/6

=5/5+1/6

=1+1/6

=7/6

9/13+4/13+2/3

=(9/13+4/13)+2/3

=13/13+2/3

=1+2/3

=5/3

k mk nha các bạn, nhớ kb mk đó

Answer 3

2/5+1/6+3/5=(2/5+3/5)+1/6

                   =1+1/6=7/6

9/13+4/13+2/3

=(9/13+4/13)+2/3

=1+2/3=5/3

Answer 4

đưa các số có chung mẫu vào trong ngoặc

(2/5+3/5)+1/6=5/5+1/6=1+1/6=1/1+1/6=6/6+1/6=7/6

(9/13+4/13)+2/3=13/13+2/3=1/1+2/3=3/3+2/3=5/3

vậy thôi giải đáp án luôn rồi 

Answer 5

2/5+1/6+3/5=[2/5+16]+1/6=1+1/6=7/6

9/13+4/13+2/3=[9/13+4/13]+2/3=1+2/3=5/3