308
cho A = 1/2 + 1/3 + ... +1/308
B = 308/1 + 307/2 + ... + 1/308
tìm A/B
308/1+307/2+306/3+...+2/307+1/308
=> A= (1+1+... +1) +307/2+306/3+...+1/308
308 số 1
=> A= ( 1+307/2 )+(1+306/3 )+..+(1+1/308) +1
=> A = 309/2 +309/3 +...+ 309/308 +309/309
=> A = 309(1/2+1/3+...+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
cho A =1/2 +1/3 +1/4 +.....+1/308+1/39
B = 308/1 +307/2 +.....+3/306 +2/307+1/308.Tính a+b
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+...+1/308+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
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+...+1/308+1/309
B= 308/1+307/2+...+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+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+2/307+1/308
Tính A/B ? ( Có cách làm )