-1,8/5,-15/7,24/9… What is the general term formula of?

-1,8/5,-15/7,24/9… What is the general term formula of?

a1=-3/(2*1+1)
a2=8/5=(3+5)/(2*2+1)
a3=-15/7=-(3+5+7)/(2*3+1)
a4=24/9=(3+5+7+9)/(2*4+1)
...
an=(-1)^n*[3+5+7+...+(2n+1)]/(2n+1)
=(-1)^n*[n(n+1)+n]/(2n+1)
=(-1)^n*(n^2+2n)/(2n+1)

-A general formula of 1,8 / 5, - 15 / 7,24 / 9 is

-3 / 38 / 5-15 / 724 / 9 has (- 1) ^ n. if the signed molecule is an-a (n-1) = 2n + 1, then a (n-1) - A (n-2) = 2 (n-1) + 1 = 2N-1 A3-a2 = 7a2-a1 = 5 = 2 * 2 + 1 add an-a1 = 2 [n + (n-1) + +2] + 1 * (n-1) = 2 * n (n-1) / 2 + n-1 = n ^ 2-1, the denominator is 2n + 1, so (- 1) ^ n * (n ^ 2-1) / (2n + 1)

7.5 * 0.8 = 6, 3.84 / 4.8 = 0.8 are listed as a comprehensive formula
26.4-1.4 = 25, 5.4 / 4 = 1.4, and the comprehensive formula is also listed

The length ratio of the three sides of the triangle is 3:4:5,

1.25 × 7.3 × 0.8

1.25x0.8x7.3=0.1x7.3=0.73

4 / 19 times 16 / 13 minus 6 / 19 times 2 / 13

(4/19×16/13)-(6/19×2/13)
=(4×16-6×2)/19×13
=52/19×13
=4/19

If 4x ^ 3 + 9x ^ 2 + MX + n can be divided by (x + 3) (x-1), find the nth power of M

Let 4x & sup3; + 9x & sup2; + MX + n = a (x + 3) (x-1) x = - 3, x + 3 = 0, so the right side is equal to 0, then the left side is equal to 0x = - 3, and the left side = - 108 + 81-3m + n = 03m-n = - 27 (1) similarly, when x = 1, the left side is equal to 0, so 4 + 9 + m + n = 0m + n = - 13 (2) (1) + (2) 4m = - 40m = - 10N = - 13-m = - 3

4. 9; 5; 4 and 10; 6; 8; 10 two groups of numbers to find 24 answers

4. The 24 point answers of 9; 5; 4 and 10; 6; 8; 10
\x09
Routine has no answer
\x09
Unconventional has answers:
9-4-5+4!=24
√10*10 +8+6=24

We know that the geometric meaning of the formula | x-3 | is to represent the point of X and the number 3 on the number axis

According to the meaning of absolute value, we can know that | X-2 | is the distance between the point representing the number x and the point representing the number 2 on the number axis, and | x + 1 | is the distance between the point representing the number x and the point representing the number - 1 on the number axis. Now we require the minimum value of | X-2 | + | x + 1 |. According to the nature of line segment, the shortest line segment between two points, we can know that when - 1 ≤ x ≤ 2, | X-2 | + | x + 1 | has the minimum value, |X-2 | + | x + 1 | has a minimum
Then | X-2 | = 2-x, | x + 1 | = x + 1,
Comment: this question examines the meaning of absolute value and the nature of line segment, so it is difficult

What's 12 to 8? What's 9 to 15

12:8=x:9
x=13.5
12/8=15/y
y=10
So 12:8 = 13.5:9 = 15 / 10
If you don't understand, please ask!

On the polynomial X & sup2; - MXY + 2xy-y of X and y, the 2N-1 power + 1 is a cubic trinomial

From the fact that the polynomial X & sup2; - MXY + 2XY - y of X and Y is a cubic trinomial, we can see that
2N-1 = 3 and - MXY + 2XY = 0,
M = 2, n = 2
So, M + n = 4