Chứng minh : 7/12<1/41+1/42+1/43+........+1/80<1
Chứng minh rằng: 1/41+1/42+1/43+..........+1/79+1/80>7/12
Chứng minh : 7/12<1/41+1/42+1/43+...+1/80 <1
Chứng minh: \(\dfrac{7}{12}< \dfrac{1}{41}+\dfrac{1}{42}+\dfrac{1}{43}+...+\dfrac{1}{80}< 1\)
Chứng minh rằng :
1/41 + 1/42 + 1/43 + ... + 1/79 + 1/80 > 7/12
chứng minh rằng:
1/41+1/42+1/43+.....+1/79+1/80 >7/12
Chứng minh rằng :
1/41+ 1/42+ 1/43+ .................... +1/80 >7/12
1,Chứng minh rằng:
1/2<1/51+1/52+...+1/100<1
2,Chứng minh 1/41+1/42+1/43+...+1/79+1/80>7/12
Chứng minh rằng:
a)A=1/11+1/12+1/13+...+1/20>1/2 b)B=1/41+1/42+1/43+...+1/80>7/20