A topic of finding rules 1. - 2, 3, - 4, 5, - 6, 7, - 8. How should the nth number be represented? Let's use a formula

A topic of finding rules 1. - 2, 3, - 4, 5, - 6, 7, - 8. How should the nth number be represented? Let's use a formula

The first number is positive, the second number is negative, so we can use (- 1) ^ (n + 1) to determine their positive and negative
So the nth number should be expressed as [(- 1) ^ (n + 1)] * n

Give me a few questions about the rational number application in the first semester of junior high school
10 questions of oral arithmetic, 5 questions of calculation and 3 questions of application

1、 Oral calculation - (- 13) & sup2; = - 16 △ 0.125 = 2 / 35 × 35% = 99 × 1% + 1% = 24 × (1 / 3 + 1 / 4 + 1 / 6) = 21 × 5 / 13 + 42 × 4 / 13 = - 2 × (- 3) × (- 20) = √ (- 25) & sup2; = 375% × 4 / 3 × 2 = 12.5% × 32 × 0.25 = 2

Find the law of rational number
1、-1、2、-6、24、——

1、-1、2、-6、24、-120
1*(-1)=-1
(-1)*(-2)=2
2*(-3)=-6
(-6)*(-4)=24
24*(-5)=-120