A = \(\frac{3}{1\times3}\) + \(\frac{3}{3\times5}\) + ... + \(\frac{3}{97\times99}\) + \(\frac{3}{99\times101}\)

A = \(\frac32\) x (\(\frac{2}{1\times3}\) + \(\frac{2}{3\times5}\) + ... + \(\frac{3}{99\times101}\))

A = \(\frac32\) x (\(\frac11\) - \(\frac13\) + .. + \(\frac{1}{99}\) - \(\frac{1}{99}-\frac{1}{101}\))

A = \(\frac32\) x (\(\frac11\) - \(\frac{1}{101}\))

A = \(\frac32\) x \(\frac{100}{101}\)

A = \(\frac{150}{101}\)

Theo công thức là ra nhé=))

chịu

A=1x3x(5+1) + 3x5x(7-1) +5x7x(9-3) +...+ 99x101x(103-97)

6A=3+ 1x3x5 +3x5x7-1x3x5 + 5x7x9 -3x5x7 +....+99x101x103 - 97x99x101

6A=3+99x101x103=1019703

vậy = 1019703

nếu sai chỗ nào thì sửa hộ mk vs

Đặt biểu thức = A

6A = 1x3x6 + 3x5x6+....+ 97x99x6

= 1x3x(1+5) + 3x5x(7-1) + 5x7x(9-3) +.....+ 97x99x(101-95)

= 1x3+1x3x5+3x5x7-1x3x5+5x7x9-3x5x7+.....+97x99x101-95x97x99

= 1x3+97x99x101

= 969906

=> A = 161651

k mk nha

A=1x3 +3x5 +5x7 +....+99x101

6A=1x3x(5+1) + 3x5x(7-1) +5x7x(9-3) +...+ 99x101x(103-97)

6A=3+ 1x3x5 +3x5x7-1x3x5 + 5x7x9 -3x5x7 +....+99x101x103 - 97x99x101

6A=3+99x101x103=1019703

A=1x3+3x5+5x7+...+99x101

Ax6=1x3x6+3x5x6+5x7x6+....+99x101x6

Ax6=1x3x(5+1)+3x5x(7-1)+5x7x(9-3)+...+99x101x(103-97)

Ax6=1x3x5+1x1x3+3x5x7-1x3x5+5x7x9-3x5x7+..+99x101x103-97x99x101

Ax6=1x3x1+99x101x103

Ax6=3+1029897

Ax6=1029900

A=1029900:6

A=171650

(Đặt A là tên biểu thức)