Question

[IceAnh]

tinh A

A=\(\frac{3^2}{1.4}\)+\(\frac{3^2}{4.7}\)+\(\frac{3^2}{7.10}\)+\(\frac{3^2}{10.13}\)+.......+\(\frac{3^2}{97.100}\)

Answer 1

[Trúc Giang]

= \(3\left(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{97.100}\right)\)

= \(3\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{100}\right)\)

= \(3\left(1-\frac{1}{100}\right)\)

= \(3\left(\frac{100}{100}-\frac{1}{100}\right)\)

= \(3.\frac{99}{100}\)

= \(\frac{297}{100}\)

Answer 2

[ღ๖ۣۜLinh's ๖ۣۜLinh'sღ] ★we are one★]

\(A=3\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{100}\right)\)

\(A=3\left(1-\frac{1}{100}\right)=3.\frac{99}{100}=\frac{297}{100}\)