A = 1/31 + 1/32 + ... + 1/60
A = (1/31 + 1/32 + ... + 1/40) + (1/41 + 1/42 + ... + 50) + (1/51 + 1/52 + ... + 1/60)
A > 1/40 × 10 + 1/50 × 10 + 1/60 × 10
A > 1/4 + 1/5 + 1/6
A > 1/4 + 1/6 + 1/6
A > 1/4 + 1/3
A > 7/12
cho A = 1/31 + 1/32 + 1/33 + ... + 1/60 CMR : A > 7/12
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
\(Cho A = 1/30 + 1/31 + 1/32 +...+ 1/60. Cm A > 7/12\)
cho \(A=\frac{1}{31}+\frac{1}{32}+\frac{1}{33}+...+\frac{1}{60}\)
chứng minh rằng \(A>\frac{7}{12}\)
CMR:
1/31+1/32+1/33+...+1/60 > 7/12
Cho:A=1/31+1/32+1/33+..............+1/60
Chứng minh rằngA>7/12
chưgs minh rằng :
1/31+1/32+1/33+.....+1/60>7/12
Chứng tỏ rằng
7/12<1/31+1/32+1/33+... +1/59+1/60<5/6
PLEASE, HELP ME
