\(A=\frac{1}{31}+\frac{1}{32}+\frac{1}{33}+...+\frac{1}{60}\)
\(=\left(\frac{1}{31}+\frac{1}{32}+...+\frac{1}{45}\right)+\left(\frac{1}{46}+...+\frac{1}{60}\right)>\frac{1}{45}.15+\frac{1}{60}.15=\frac{1}{3}+\frac{1}{4}=\frac{7}{12}\)
=>đpcm
l-i-k-e cho mình nha
A=1/31+1/32+1/33+...+1/60. chứng minh A>7/12
cho A= 1/31+1/32+1/33+.....+1/60
chứng minh rằng A> 7/12
chưgs minh rằng :
1/31+1/32+1/33+.....+1/60>7/12
cho A = 1/31 + 1/32 + 1/33 + ... + 1/60 CMR : A > 7/12
CMR:
1/31+1/32+1/33+...+1/60 > 7/12
cho \(A=\frac{1}{31}+\frac{1}{32}+\frac{1}{33}+...+\frac{1}{60}\)
chứng minh rằng \(A>\frac{7}{12}\)
Cho S= 1/31+1/32+1/33+......................+1/100 .Chứng minh S<7/3
Chứng tỏ rằng
7/12<1/31+1/32+1/33+... +1/59+1/60<5/6
PLEASE, HELP ME
câu trả lời cho câu hỏi của Huong Le Thị Lan: 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32.
=(1+32)+(2+31)+(3+30)+(4+29)+(5+28)+(6+27)+(7+26)+(8+25)+(9+24)+(10+23)+(11+22)+(12+21)+(13+20)+(14+19)+(15+18)+(16+17)
=33+33+33+33+33+33+33+33+33+33+33+33+33+33+33+33. =33.16 (dấu chấm là dấu nhân)=528
