Question

Tính tổng:

P = 2 x 4 + 4 x 6 + 6 x 8 +...+ 98 x 100

Answer 1

\(\Rightarrow6P=2.4.6+4.6.6+...+98.100.6\)

\(=2.4.6+4.6.\left(8-2\right)+...+98.100.\left(102-96\right)\)

\(=2.4.6+4.6.8-2.4.6+...+98.100.102-96.98.100\)

\(=98.100.102\)

\(\Rightarrow P=\frac{98.100.102}{2}=499800\)

Answer 2

Nhầm phải là \(\frac{98.100.102}{6}=166600\)

xin lỗi ghi nhầm

Answer 3

\(P=2\cdot4+4\cdot6+6\cdot8+...+98\cdot100\)

\(P=\frac{98\cdot100\cdot102}{6}=166600\)