Question

cho A= 4 / 7.31 + 6 / 7.41 + 9 / 10.41 + 7 / 10.57 và B= 7 / 19.31 + 5 / 19.43 + 3 / 23.43 +11 /23.57

a) Chứng tỏ rằng A/5 = 1/3 -1/57

b) Tính A/B

Giúp mình nhé ^^.

 

Answer 1

Bai de vcl

A=4/7.31+6/7.41+9/10.41+7/10.57

A=20/35.31+30/35.31+45/50.41+35/50.57

A=5.(4/35.31+6/35.41+9/50.41+7/50.57)

=5.(1/31-1/35+1/35-1/41+1/41-1/50+1/50-1/57)

A=5.(1/31-1/57)

B=7/19.31+5/19.43+3/23.43+11/23.57

B=14/34.31+10/38.43+6/46.43+22/46.57

B=2.(7/34.31+5/38.43+3/46.43+11/46.57

B=2.(1/31-1/34+1/34-1/43+1/43-1/46+1/46-1/57)

B=2.(1/31-1/57)

    5.(1/31-1/57)

Vay A/B=5/2

dau /la phan so do