The general formula of 1 5 13 25

The general formula of 1 5 13 25

When n = 1,
f(n)=1
When n > = 2,
f(n)=f(n-1)+4×(n-1)
For example:
f(2)=f(1)+4×(2-1)=1+4×1=5
f(3)=f(2)+4×(3-1)=5+4×2=13
f(4)=f(3)+4×(4-1)=13+4×3=25
The difference between two adjacent terms is an integral multiple of 4
a1＝1
a2＝a1＋4×1
a3＝a2＋4×2
……
an＝a(n-1)＋4(n-1)
Stack, get
General term formula an = 1 + 2n (n-1)

1,5,13,25,… The general formula is?

an=1+2*n*(n-1);
an-a(n-1)=4*(n-1);
a(n-1)-a(n-2)=4*(n-2);
.
a2-a1=4*1
So an-a1 = 4 * (1 + 2 + 3 +... + (n-1)) = 4 * n * (n-1) / 2
an=an=1+2*n*(n-1);

X = - 4, y = quarter, find the value of the square of (x multiplied by X to the power of n) multiplied by (y to the power of N + 1)
That is: x = - 4, y = 1 / 4, find the value of (x * x ^ n) ^ 2 (y ^ n + 1) ^ 2

(x*x^n)^2*y^(n+1)^2
=(-4)^(2n+2)*(1/4)^(2n+2)
=(-4*1/4)^(2n+2)
=(-1)^(2n+2)
=[(-1)^2]^(n+1)
=1^(n+1)
=1

The second volume of the sixth grade

Use your own brain, I can only help you think of three
The branches are black
Open your knees, legs and limbs
Next you think, don't rely too much on others, that brain will rust! This is not a joke!
Don't copy mine! These are all from me word by word!
I don't log in because I don't keep my name when I do a good job!

Given that O is the origin of coordinates, a (- 3,2) B (3,4), then the coordinates of vertex C of parallelogram oabc are
We have to do it with vectors

The opposite sides of parallelogram are parallel and equal
There is
Vector AB = vector OC,
Vector AB = B-A = (6,2)
Let OC = AB = (6,2)
also
Vector OC = C-O = (x, y) - (0,0) = (6,2)
thus
x=6,y=2
therefore
C（6,2）
The team will answer the questions for you
Please click the [select as satisfactory answer] button below

1999 * 199.8-1998 * 199.7

=199.8 (1999-10 * 199.7)
=199.8*2
=399.6

Answers to the homework book of primary school Chinese (Volume 2) (ancient poetry recitation review volume) (84-86)
Start with the sixth question and do the tenth

1： Steaming, melting, withering jadeite, preparing for firecracker exhibition, horror, cruelty, mourning, freezing and stifling, clever sobbing, Christmas tree, excellent troops, simple administration, full of vitality, sincere and sincere, Zhang dengjiecai, insightful and insightful

In square ABCD, M is the midpoint of AB, e is a point on the extension line of AB, Mn is perpendicular to DM, and the bisector of intersection CBE is n
Don't use similarity, share garden
It is suggested that: take the midpoint F of AD and connect FM. First prove △ DFM ≌ △ MBN, then prove MD = Mn

Simple calculation of recurrence equation of 2.5 + 25 * 1.65

2.5+25*1.65
=2.5+2.5*16.5
=2.5*(1+16.5)
=2.5*17.5
=43.75
To adopt the first correct answer is to respect the labor of the respondents. I wish you progress!

(2 √ 3-3 √ 2) (√ 3 - √ 2) quadratic radical operation

(2√3-3√2) (√3-√2)
=6-2√6-3√6+6
=12-5√6