Simple operation of 1 × 3 / 1 + 3 × 5 / 1 + 5 × 7 / 1 + 7 × 9 / 1 + 9 × 11 / 1 + 11 × 13 / 1

Simple operation of 1 × 3 / 1 + 3 × 5 / 1 + 5 × 7 / 1 + 7 × 9 / 1 + 9 × 11 / 1 + 11 × 13 / 1

It should be 1 / (1 * 3) + 1 / (3 * 5) + 1 / (5 * 7) + 1 / (7 * 9) + 1 / (9 * 11) + 1 / (11 * 13). 1 / (1 * 3) = (1 / 1-1 / 3) / 21 / (3 * 5) = (1 / 3-1 / 5) / 2.1 / (11 * 13) = (1 / 11-1 / 13) / 2, so the original formula = (1 / 1-1 / 3) / 2 + (1 / 3-1 / 5) / 2 +. + (1 / 11-1 / 13) / 2 = (1 / 1-1 / 13) / 2 = 6 / 13

Calculation: 9 ﹣ 13 + 13 ﹣ 9 + 11 ﹣ 13 + 14 ﹣ 9 + 6 ﹣ 13=______ ．

So the answer is: 5

Simple operation of 5 / 14 * 9 / 11 + 13 / 14 * 5 / 11
"/" is not a division sign, but a fractional line

= 9/14*5/11+13/14*5/11
=5/11*（9/14+13/14）
=5/11*22/14
=5/11*11/7
=5/7
I hope I can help you,