Find rules 1, 1, 2, 3, 4, 7, () Please write down the process and how you think about the calculation so that I don't understand it If it's 11, 2 + 3 = 5, shoot directly. You have to say what you think and prepare for the Jiaochuan academy entrance examination, so you need to know the calculation process. Choice: a 6 B 8 C 9 d 11, pay attention to the choice, only these four answers. Choose 11 to ignore, repeat, 2 + 3 = 5!

Find rules 1, 1, 2, 3, 4, 7, () Please write down the process and how you think about the calculation so that I don't understand it If it's 11, 2 + 3 = 5, shoot directly. You have to say what you think and prepare for the Jiaochuan academy entrance examination, so you need to know the calculation process. Choice: a 6 B 8 C 9 d 11, pay attention to the choice, only these four answers. Choose 11 to ignore, repeat, 2 + 3 = 5!

All even terms are followed by one minus one
The odd term is 1 2 4 8
Choose B

Find the law and calculate half + one sixth + one twelfth + one twentieth + one thirtieth

The original formula = 1 / 1 * 2 + 1 / 2 * 3 + 1 / 3 * 4 + 1 / 4 * 5 + 1 / 5 * 6 = 1-1 / 2 + 1 / 2-1 / 3 + 1 / 3-1 / 4 + 1 / 4-1 / 5 + 1 / 5-1 / 6 = 1-1 / 6 = 5 / 6

One half. One sixth. One twelfth. One twentieth Please find out the law. What's the ninth number? What's the fourteenth number? What's the nth number

The rule is:
The nth number is 1 / [n (n + 1)]
So the ninth is 1 / (9 * 10) = 1 / 90
The 14th is 1 / (14 * 15) = 1 / 210