Given the sequence an = 4n-2 and BN = 2 / 4 ^ (n-1), let CN = an / BN, find the first n terms and TN of the sequence {CN} I know the answer to this question is: CN = an / BN = (4n-2) / [2 / 4 ^ (n-1)] = (n-1) 4 ^ (n-1) Tn=0+1*4+2*4^2+3*4^3+.+(n-1)4^(n-1) 4Tn=1*4^2+2*4^3+3*4^4…… (n-1)4^n Tn-4Tn=4+4^2+4^3+...+4^(n-1)-(n-1)4^n -3Tn=4[1-4^(n-1)]/(1-4)-(n-1)4^n Tn=(n-1)4^n/3-(4^n-4)/9 The key is that I can't understand this step - 3tn = 4 [1-4 ^ (n-1)] / (1-4) - (n-1) 4 ^ n TN is obviously less than 4tn. How can the right side be positive after subtraction? Can you tell me how - 3tn = 4 [1-4 ^ (n-1)] / (1-4) - (n-1) 4 ^ n comes from.. I've been watching it for more than an hour. I just don't know..

Given the sequence an = 4n-2 and BN = 2 / 4 ^ (n-1), let CN = an / BN, find the first n terms and TN of the sequence {CN} I know the answer to this question is: CN = an / BN = (4n-2) / [2 / 4 ^ (n-1)] = (n-1) 4 ^ (n-1) Tn=0+1*4+2*4^2+3*4^3+.+(n-1)4^(n-1) 4Tn=1*4^2+2*4^3+3*4^4…… (n-1)4^n Tn-4Tn=4+4^2+4^3+...+4^(n-1)-(n-1)4^n -3Tn=4[1-4^(n-1)]/(1-4)-(n-1)4^n Tn=(n-1)4^n/3-(4^n-4)/9 The key is that I can't understand this step - 3tn = 4 [1-4 ^ (n-1)] / (1-4) - (n-1) 4 ^ n TN is obviously less than 4tn. How can the right side be positive after subtraction? Can you tell me how - 3tn = 4 [1-4 ^ (n-1)] / (1-4) - (n-1) 4 ^ n comes from.. I've been watching it for more than an hour. I just don't know..

Tn-4Tn=4+4^2+4^3+...+4^(n-1)-(n-1)4^n
so
The key is the size of {4 + 4 ^ 2 + 4 ^ 3 +... + 4 ^ (n-1)}
They are an equal ratio sequence. You can search the formula for the sum of the first n terms of the equal ratio sequence
a+aq^1+aq^2+...+aq^(n-1) = a(1-q^n)/(1-q)

Is the sum of two odd numbers odd or even

You can give examples. For example, 1 plus 1 equals 2 (even number) and 3 plus 3 equals 6 (even number) are even numbers

The sum of any two odd numbers must be even______ (judge right or wrong)

According to the properties of odd and even numbers, the sum of any two odd numbers must be even

Write any two odd numbers. Is the sum of them odd or even

Odd + odd = even
Odd + even = odd
Even + even = even
It's even
I hope I can help you,

The sum of two even numbers is even, and the sum of two odd numbers is odd,

Even plus even is even odd plus odd is even

What is the difference between the sum of the first 40 positive odd numbers 1 + 3 + 5 and the sum of the first 40 positive even numbers: 2 + 4 + 6

(1-2)+(3-4)+(5-6).+(79-80)=-1x40=-40

The difference between the reciprocal of two consecutive odd numbers is 2 / 255, so what are the two consecutive odd numbers?

Suppose that the two consecutive odd numbers are X-1 and X + 1, respectively
So their reciprocal difference is 1 / (x-1) - 1 / (x + 1)
=[(x+1)-(x-1)]/(x+1)(x-1)
=2/(x^2-1)
=2/255
So x ^ 2-1 = 255
x^2=256
x=±16
So these two consecutive odd numbers are - 17, - 15 or 15, 17

If a is used to represent an even number (not 0), then the two odd numbers adjacent to a can be expressed as () and (): the two even numbers adjacent to a can be expressed as a table
Shown as () and ()

If a is used to represent an even number (not 0), then the two odd numbers adjacent to a can be expressed as (A-1) and (a + 1): the two even numbers adjacent to a can be expressed as (A-2) and (a + 2)

If an odd number is represented by a, then the two even numbers adjacent to a are () and (), and the two odd numbers adjacent to a are () and ()

A-1 and a + 1
A-2 and a + 2

If a is an even number greater than 2, then the two even numbers adjacent to a are____ And___ The two odd numbers adjacent to a are_____ And______

a-2 a+2
a-1 a+1