Cho A= 1/2+1/3+1/4+1/5+...+1/308+1/309
B=308/1+307/2+306/3+305/4+...+3/306+2/307+1/308
Tính A/B
Cho A = 1/2 + 1/3 + 1/4 + 1/5 + ............ + 1/308 + 1/309
B = 308/1 + 307/2 + 306/3 + ................... + 3/306 + 2/207 + 1/308
Tính A/B
Cho:
A=1/2+1/3+1/4+1/5+...+1/308+1/309
B=308/1+307/2+306/3+...+3/306+2/307+1/308
Tính A/B ? ( Có cách làm )
cho A=1/2+1/3+1/4+...+1/308+1/309
B=308/1+307/2+306/3+...+3/306+2/307+1/308
tim A/B
A= 1/2 +1/3+1/4+1/5+....+1/308+1/309
Tính A= 1/2+1/3+1/4+1/5+.....+1/308+1/309
bài 1:A= 1/2+1/3+1/4+...+1/308+1/309
B= 309/1+308/2+307/3+...+1/309
tính A/B
bài 2: G=5/3+8/32+11/32+...+302/3100
bài 3: cho A= 2/3+8/9+26/27+...+3n-1/3n
chứng minh A>n-1/2
Cho A= 1/2+1/3+1/4+...+1/308+1/309
B= 308/1+307/2+...+2/307+1/308
Tính A/B
A=1/2+1/3+1/4+...+1/308+1/309
B=308/1+307/2+306/3+...+3/306+2/307+1/308
Tính A/B.
Ta phân tích 308 thành 308 số 1 rồi nhóm lại
B=(1+307/2) + (1+306/3) +...+( 1+2/307) + (1+1/308) + 1=309/2+ 309/3+...+309/309
= 309( 1/2+1/3+...+ 1/308+1/309)=309A
A/B=1/309
A=1/2+1/3+1/4+...+1/308+1/309
B=308+307/2+306/3+...+3/306+2/307+1/308
Tính A/B.
bài này dễ nhưng mất tg lắm k mình trước mình làm sau cho
