\(A=\frac{1x3x5x7x...x49}{\left(26x28x...x50\right)\left(27x29x...x49\right)}=\frac{1x3x5x...x25}{26x28x30x...x50}\)

\(2xA=\frac{1x3x5x7x...x25}{\frac{26x28x30x...x50}{2}}=\frac{1x3x5x...x25}{13x14x15x...x25}=\frac{1x3x5x...x11}{14x16x18x...x24}\)

\(4xA=\frac{1x3x5x...x11}{7x8x9x...x12}=\frac{1x3x5}{8x10x12}\Rightarrow A=\frac{1x3x5}{4x8x10x12}=\frac{1}{4x8x2x4}=\frac{1}{256}\)

hết cỡ rồi ông tướng

Đồng cảnh ngộ.Huhu

Ta có : P = 1.2.2 + 2.3.3 + ....+ 99.100.100

=1.2.(3 - 1) + 2.3.(4 - 1) + ....+99.100.(101 - 1)

= (1.2.3 + 2.3.4 + .... + 99.100.101) - (2.3 + 3.4+.....+99.100)

Đặt B = 1.2.3 + 2.3.4 + 4.5.6 +...+ 99.100.101

4B = 1.2.3.(4 - 0)+2.3.4.(5 - 1) + ... + (99.100.101(102 - 98)

4B = 1.2.3.4 + 2.3.4.5 - 1.2.3.4 +...+ 99.100.101.102 - 98.99.100.101

4B = 99.100.101.102

4B = 101989800

  B = 25497450

Đặt C = 1.2 + 2.3 + 3.4 +...+ 99.100

3C = 1.2.(3 - 0) + 2.3.(4 - 1) +...+ 99.100.(101 - 98)

3C = 1.2.3 + 2.3.4 - 1.2.3 +...+ 99.100.101 - 98.99.100

3C = 99.100.101

3C = 999900

  C = 999900 : 3

  C = 333300

Vậy: A = 25497450 – 333300 = 25164150

Ta có:

\(P=1.2^2+2.3^2+3.4^2+...+99.100^2\)

\(=1.2.\left(3-1\right)+2.3.\left(4-1\right)+3.4.\left(5-1\right)+...+99.100.\left(101-1\right)\)

\(=1.2.3-1.2+2.3.4-2.3+3.4.5-3.4+...+99.100.101-99.100\)

\(=\left(1.2.3+2.3.4+...+99.100.101\right)-\left(1.2+2.3+...+99.100\right)\)

\(=25497450-333300=25164150\)

Câu hỏi của Nguyễn Thư - Toán lớp 5 - Học toán với OnlineMath

600/9702 = 100/1617

\(\frac{600}{9702}=\frac{600:6}{9702:6}=\frac{100}{1617}\)

\(\frac{600}{9702}=\frac{100}{1617}\)

me cann't help you because i'm stupid