Question

Tính A = 1.3.5 + 3.5.7 + 5.7.9 +.........+ 99.100.101

Answer 1

Ta có: A = 1.3.5 + 3.5.7 + 5.7.9 + ................ + 95.97.99
\(\Rightarrow\) 8A= 1.3.5.8 + 3.5.7.8 + 5.7.9.8 + ................ + 95.97.99.8
\(\Rightarrow\) 8A=1.3.5(7+1)+3.5.7(9-1)+5.7.9.(11-3)+.......+95.97.99(101-93)
\(\Rightarrow\) 8A=1.3.5.7+15+3.5.7.9-3.5.7+5.7.9.11-3.5.7.9+.......+95.97.99.101- 93.95.97.99
\(\Rightarrow\) 8A=15+95.97.99.101
\(\Rightarrow\) A=(
\(\Rightarrow\) A=11517600 Vậy A = 11517600

Answer 2

sai đề

Answer 3

Tính giá trị biểu thức A = 1.2.3 + 3.4.5 + 5.6.7 + … + 99.100.101