Question

tính nhanh :

a, 2/3 x 4/7 + 1/3 x 4/7 

b, 5/8 x 3/7 x 7/3

c, (4/5 + 2 ) x 5/4

Answer 1

a,4/7

b,5/8

c,7/2

Answer 2

a)2/3*4/7+1/3*4/7=(2/3+1/3)*4/7=1*4/7=4/7

b)5/8*3/7*7/3=5/8*1=5/8

c)(4/5+2)*5/4=4/5*5/4+2=1+2=3

Answer 3

a, 4/7

b,5/8

c, 7/2

Answer 4

a,Ta có:(\(\frac{2}{3}\)+\(\frac{1}{3}\)) x \(\frac{4}{7}\)

            =1 x \(\frac{4}{7}\)

            = \(\frac{4}{7}\)

b,Ta có:\(\frac{5}{8}\) x (\(\frac{3}{7}\) x \(\frac{7}{3}\))

           =\(\frac{5}{8}\) x 1

           =\(\frac{5}{8}\)

c,Ta có:\(2\frac{4}{5}\) x \(\frac{5}{4}\)

         = (\(\frac{4}{5}\) x \(\frac{5}{4}\)) x ( 2 x 1)

         = 1 x 2

         = 2

Answer 5

a, 2/3 x 4/7 + 1/3 x 4/7

= ( 2/3 x 1/3 ) + ( 4/7 x 4/7 ) 

= 3/3 + 8/7

= 1 + 8/7

= 15/7

Answer 6

câu c mình làm sai: ta có:\(\frac{4}{5}\) x  \(\frac{5}{4}\) + 2 x \(\frac{5}{4}\)

                                   =1 + \(\frac{5}{2}\)

                                   = \(\frac{7}{2}\)