Observe the following list of regular numbers 2,6,12,20,30

Observe the following list of regular numbers 2,6,12,20,30

1*2,
2*3
3*4
4*5
5*6
.
n*(n+1)=n^2+n

Write 105 in the form of multiplication of several prime numbers ()

105=3*5*7
105 in the form of multiplication of several prime numbers (3 * 5 * 7)

If and only if the image of function f (x) is symmetric with respect to the line x = (a + b) / 2

f[(a+b)/2 +x]=f[(a+b)/2 -x]

Find the rules, fill in the blanks, - 4,7, - 11,16, - 22_____ ,______
To explain the law of this problem, fill in the following two numbers

The sign alternates, the first + 3, the second + 4, the third + 5, and so on
The last two are: 29, - 37

For a natural number less than 80, the sum of it and 3 is a multiple of 5, and the difference between it and 3 is a multiple of 6?

The difference between him and 3 is a multiple of 6
The bits of this number are odd
His sum with 3 is a multiple of 5
The single digit is seven
The single digit difference from 3 is 4
24,54, divisible by 6
The natural number is 27 or 57

Taking the ground as the reference frame, the external force on the treadmill is static friction, which should produce an acceleration, but the person is still relative to the ground
Why?

People are also subject to a backward air resistance, the two balance, so static. Leg swing, friction air resistance
The work done by man is mainly consumed by swinging his legs, and the work to overcome friction is only a small amount

625 = fraction = (): () = ()% = (): ()

625 = 5 / 8 = (5): (8) = (62.5)% = (10): (16)
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Three times the sum of two adjacent even numbers is 78, so what are the two even numbers? How to set up the equation?

Hello
Let the smaller even number be X
（x+x+2）×3=78
2x+2=26
2x=24
x=12
Larger even = 12 + 2 = 14
A: the two even numbers are 12 and 14 respectively

Given that a > b > 0, prove the n-th root of a > the n-th root of B (n ∈ N and N > 1)

It is known that a > b > 0, so a / b > 1
So the nth root of a / the nth root of B = the nth root of (A / b) > the nth root of 1 = 1
So the n-th root of a is greater than the n-th root of B

1,5,7,17,31 general term formula; 3 / 4,15 / 16,35 / 36,63 / 64 general term formula; 1 / 2,1 / 6,1 / 12,1 / 20,1 / 30 general term formula

Man, it takes time to do it, 1,5,7,17,31 general term formula; 1 = 2 ^ 1-15 = 2 ^ 2 +! 7 = 2 ^ 3-117 = 2 ^ 4 + 131 = 2 ^ 5-1 general term formula should be: an = 2 ^ n + (- 1) ^ n (n belongs to positive integer) 3 / 4,15 / 16,35 / 36,63 / 64 general term formula should be: an = (n ^ 2-1) / N ^ 2 (n belongs to 2,4,6,8...) 1/...