Equal difference equal ratio sequence and related formula

Equal difference equal ratio sequence and related formula

The summation formula of arithmetic sequence Sn = n (a1 + an) / 2 or Sn = [2Na1 + n (n-1) D] / 2 note: an = a1 + (n-1) DSN = n (a1 + an) / 2 = n {a1 + [A1 + (n-1) D]} / 2 = n [2A1 + (n-1) D] / 2 = [2Na1 + n (n-1) D] / 2 should be true for any n, then SN-S (n-1) = [n (a1 + an) - (n-1) (a1 +
Who knows the formula of equal difference and equal ratio sequence
Isochromatic an = a1 + (n-1) d
Equal ratio an = A1 * q ^ n-1
Isochromatic an = a1 + (n-1) d
Equal ratio an = A1 * q ^ n-1
All formulas in arithmetic and proportional sequence
It must be all, including the tolerance and common ratio of s even / s odd and Sn, s (2n-n), s (3n-2n)
Some of the regular books are unnecessary
When the number of items is odd, s odd / s even = (n + 1) / n
When the sequence is equal ratio sequence, Sn, s (2n-n), s (3n-2n) are equal ratio sequence
When the sequence is an arithmetic sequence, Sn, s (2n-n), s (3n-2n) are also an arithmetic sequence
When the number of items is odd, Sn = median * number of items
JFD
Mixed operation for rational numbers?
The more problems, the better. Thank you
[-|98|+76+(-87)]*23[56+(-75)-(7)]-(8+4+3) 5+21*8/2-6-59 68/21-8-11*8+61 -2/9-7/9-56 4.6-(-3/4+1.6-4-3/4) 1/2+3+5/6-7/12 [2/3-4-1/4*(-0.4)]/1/3+2 22+(-4)+(-2)+4*3 -2*8-8*1/2+8/1/8 (2/3+1/2)/(-1/12)*(-1...
Simple operation of division
Can continuous division be the product of division and multiplication?
a/b/c=a*c/b
All about it, final exam
Vt ^ 2-VO ^ 2 = 2As an object is accelerating uniformly over a distance S. then the square of the final velocity minus the square of the initial velocity is equal to twice the distance multiplied by the acceleration. VA = (VO + VT) / 2 = V (T / 2) the average velocity is equal to the average of the initial velocity and the final velocity, which is also equal to the instantaneous velocity at t / 2. S2-s1 = at ^ 2 an object is accelerating uniformly
The order of mixed operation of rational numbers
1: Do bracket, first small bracket, then middle bracket, then big bracket;
2: The operation of power;
3: Do multiplication and division;
4: Add and subtract
Simple operation of fractional division
2/5÷（3/4+2/5）
What if you open the brackets
How about the normal budget
It seems that the number is different
2/5÷（3/4+2/5）
=1÷（3/4÷2/5+2/5÷2/5）
=1÷（15/8+1）
=1÷23/8
=8/23
The first 3S passes through the distance S1, the last 3S passes through the distance S2, s2-s1 = 1.2, S1: S2 = 3:7,
Initial velocity VO = 0
First three second displacement S1
Last three second shift S2
S2 - S1 = 1.2m
S1 ：S2 =3 ：7
Let the acceleration be a and the total time be t
Then: S1 = 0.5xax3 & # 178; = 4.5a
The final velocity is:
Last three seconds last velocity v = at
Initial velocity in the last three seconds V1 = V - 3A = at - 3A
Last three seconds displacement S2 = average velocity X3s = 0.5 (V1 + V) x 3 = 0.5x (at - 3A + at) X3 = 3At - 4.5a
S1 = 4.5a
S2 = 3at - 4.5a
S2 - S1 = 1.2m
That is: 3At - 4.5a - 4.5a = 1.2
3at - 9a = 1.2
at - 3a = 0.4 ---------①
S1 ：S2 = 3 ：7
That is: 4.5a / (3At - 4.5a) = 3 / 7
4.5/(3t -4.5) = 3 / 7
4.5x7 = (3t -4.5)x3
31.5 = 9t - 13.5
9t = 45
T = 5 seconds
If at - 3A = 0.4
5a - 3a = 0.4
2a = 0.4
a = 0.2 m/s²
Read the teacher's notes more.
It's not difficult for senior one physics. At the beginning, we just introduced the concept of acceleration. As long as we deepen our understanding of this concept, and then apply several velocity displacement formulas and time displacement formulas, it's basically no problem. And it is not difficult, but if the foundation of senior one is not good, it may be more difficult in the future~
1 standard atmospheric pressure boiling water, mercury surface at 60 grid: that is, 60 scale corresponding to 100 ℃
Therefore, for each scale, that is, for each grid change, the temperature change is (100-0) / (60-10) = 2 ℃
The lowest temperature scale is 0 scale, which is 10 grids less than 0 ℃ scale, and the temperature is reduced by 10 * 2 = 20 degrees
Therefore, the minimum value of thermometer is - 20 ℃
Y = (Y2 + Y1) / (x2-x1) * (x-x2) + Y2 is the linear equation of AE
Let y = 0, then x = x2-y2 (x2-x1) / (Y2 + Y1)
There are two ways to combine the two
x=[2x1x2-4(x1+x2)]/(x1+x2-8) ⑤
It can be seen from the integrated quadratic equation of one variable
x1x2=(64k^2-12)/(3+4k^2)
x1+x2=32k^2/(3+4k^2) ⑥
A fraction application problem! Quick
Among them, 50 trees are planted in class 1 and 40 trees are planted in class 2. Q: how many more trees are planted in class 1 than in class 2? How many less trees are planted in class 2 than in class 1?
（50-40）/40=1/4
（50-40）/50=1/5
The quantity after the word "Bi" is taken as the divisor