Question

B=5/1.2+5/2.3+..........+5/99.100. Tính B

Giải gấp giùm mik

Answer 1

1/5 .B=1/1×2+1/2×3+.....+1/99×100

1/5 .B=2-1/1×2+3-2/2×3+......+100-99/99×100

1/5 .B=1/1-1/2+1/2-1/3+......+1/99-1/100

1/5.B=1-1/100

1/5. B=99/100

B=99/100÷1/5

B=99/20

Answer 2

\(B=\frac{5}{1.2}+\frac{5}{2.3}+.....+\frac{5}{99.100}\)

\(B=5-\frac{5}{2}+\frac{5}{2}-\frac{5}{3}+.....+\frac{5}{99}-\frac{5}{100}\)
\(B=5-\frac{5}{100}\)

\(B=\frac{500}{100}-\frac{5}{100}\)

\(B=\frac{495}{100}=\frac{99}{20}\)