Question

Tính C:

C= 4/1.3 + 9/2.4 + 16/3.5 + ..... + 2401/48.50

Answer 1

\(C=\frac{1.3+1}{1.3}+\frac{2.4+1}{2.4}+\frac{3.5+1}{3.5}+...+\frac{47.49+1}{47.49}+\frac{48.50+1}{48.50}\)

\(=1+\frac{1}{1.3}+1+\frac{1}{2.4}+1+\frac{1}{3.5}+...+1+\frac{1}{47.49}+1+\frac{1}{48.50}\)

\(=48+1-\frac{1}{3}+\frac{1}{2}-\frac{1}{4}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{47}-\frac{1}{49}+\frac{1}{48}-\frac{1}{50}\)

\(=48+1+\frac{1}{2}-\frac{1}{49}-\frac{1}{50}=...\)

Answer 2

\(C=\frac{4}{1.3}+\frac{9}{2.4}+\frac{16}{3.5}+...+\frac{2401}{48.50}\)

\(C=\frac{2.2}{1.3}+\frac{3.3}{2.4}+\frac{4.4}{3.5}+...+\frac{49.49}{48.50}\)

\(C=\frac{2.3.4...49}{1.2.3...48}+\frac{2.3.4...49}{3.4.5...50}=49+\frac{2}{50}=\frac{49}{25}\)

Answer 3

thankyou mn rất nhìu