Question

1/2x4+1/4x6+1/6x8+...+1/96x98+1/98x100=?

Answer 1

\(\frac{1}{2x4}\)+ \(\frac{1}{4x6}\)+ ... + \(\frac{1}{98x100}\)= \(\frac{1}{2}\)x(\(\frac{4-2}{2x4}\)+\(\frac{6-4}{4x6}\)+ ... + \(\frac{100-98}{98x100}\))

                                                        = \(\frac{1}{2}\)x(\(\frac{1}{2}\)-\(\frac{1}{4}\)+\(\frac{1}{4}\)-\(\frac{1}{8}\)+ ... + \(\frac{1}{98}\)-\(\frac{1}{100}\))

                                                        = \(\frac{1}{2}\)x(\(\frac{1}{2}\)-\(\frac{1}{100}\)) = \(\frac{49}{200}\)

Answer 2

kết quả là 49/50

Answer 3

49'/50

Answer 4

đặt A với biểu thức trên]

nhân cả 2 vế với 2 ta có

Ax2=\(\frac{2}{2x4}\)+\(\frac{2}{4x6}\)+...........+\(\frac{2}{98x100}\)

Ax2=\(\frac{1}{2}\)-\(\frac{1}{4}\)+\(\frac{1}{4}\)-\(\frac{1}{6}\)+...........+\(\frac{1}{98}\)-\(\frac{1}{100}\)

Ax2=\(\frac{1}{2}\)-\(\frac{1}{100}\)

Ax2=\(\frac{49}{100}\)

A=\(\frac{49}{100}\):2

A=0.245

Answer 5

Mình giải ra rồi 49/200 mới đúng.

Answer 6

Thank you very much!