Tính:
A=1*2*3+2*3*4+3*4*5+......+98*99*100
CMR:
A=1/4+1/16+1/36+1/64+1/100+1/144+1/196<1/2
CMR:\(\frac{1}{4}+\frac{1}{16}+\frac{1}{36}+\frac{1}{64}+\frac{1}{100}+\frac{1}{144}+\frac{1}{196}< \frac{1}{2}\)
CMR : \(\frac{1}{4}+\frac{1}{16}+\frac{1}{36}+\frac{1}{64}+\frac{1}{100}+\frac{1}{144}+\frac{1}{196}< \frac{1}{2}\)
Cho
A= 1/4+1/16+1/36+1/64+1/100+1/144+1/196+1/256+1/324+1/400. Chứng minh A < 1/20
1/4+1/16+1/1/36+1/64+1/140+1/144+1/196<1/2
chứng minh rằng a 1/4 +1/16+1/36+1/64+1/100+1/144 +1/196+......+1/10000 <1/2
CM:1/4+1/16+1/36+1/64+1/100+1/144+1/196+......+1/1000<1/2
So sánh
1/1×2×3 + 1/2×3×4 + 1/3×4×5 +...... 1/ 23×24×25 và 1/4
1/4 + 1/16+ 1/36 + 1/64 + 100 +1/144 + 1/196 và 1/2
chứng minh rằng
1/4+1/16+1/36+1/64+1/100+1/144+1/196<1/2