Let a = {x | 2x2 + ax + 2 = 0}, B = {x | x2 + 3x + 2A = 0}; if a ∪ B = {12, − 5, 2}, find a ∩ B

Let a = {x | 2x2 + ax + 2 = 0}, B = {x | x2 + 3x + 2A = 0}; if a ∪ B = {12, − 5, 2}, find a ∩ B

Let X1 and X2 be two of the equations 2x2 + ax + 2 = 0, then x1x2 = 1. From x1, X2 ∈ {12, − 5, 2} we know that two of the equations 2x2 + ax + 2 = 0 are 12, 2 respectively, that is, a = {12, 2} so − A2 = 12 + 2 {a = − 5 (8 points), then B = {x | x2 + 3x + 2A = 0} = {x | x2 + 3x-5 = 0} = {- 5, 2} so a ∩ B = {2} (12 points)

If y = x is the tangent of the curve y = x-3x + ax, then a =?

Substitute y = x into y = x-3x + ax to get x = x-3x + ax, that is, x-3x + ax-x = 0, Let f (x) = x-3x + ax-x take the derivative of F (x), Let f '(x) = 3x-6x + A-1, Let f' (x) = 0, that is, 3x-6x + A-1 = 0, because y = x is the tangent of the curve y = x-3x + ax, so f '(x) = 0 has a unique solution. In this case, B ^ 2-4ac = 0, that is (- 6) ^ 2-4 * 3 * (A-1) = 0, that is, 36-12 * (A-1) = 0, and the solution is a = 4 I made a mistake. Tell me the answer. Ask: the answer is 1 or 13 / 4. I only achieved a = 13 / 4. Answer: in F (x) = x-3x + ax-x = x (x-3x + A-1) = 0, when x = 0, the solution is a = 1. When x is not equal to 0, about an X. at this time, x-3x + A-1 = 0 has a unique solution. Therefore, B ^ 2-4ac = 0, that is (- 3) ^ 2-4 * 1 * (A-1) = 0, the solution is a = 13 / 4. In conclusion, a = 1 or 13 / 4
Adopt

How to calculate 29 divided by 30 of 29 minus 1 of 30

29÷30/29-1/30
=（30-1）×29/30-1/30
=30×29/30-1×29/30-1/30
=29-（29/30+1/30）
=29-1
=28

What are the characteristics of the odd and even terms of the equal sum sequence
In addition, in the equal sum sequence, if the first term equals a and the second term equals B, find the sum of its first n terms

If the first term equals a and the second term equals B
Then the odd term is equal to a and the even term is equal to B
Sum up
N is an odd number, s = (n + 1) a / 2 + (n-1) B / 2
N is an even number, s = (a + b) n / 2

Master Wang has 118 pieces of RMB of 2 yuan, 5 yuan and 10 yuan, totaling 500 yuan, of which 5 yuan is equal to 10 yuan. How many pieces of each of the three kinds of RMB?

70 sheets for 2 yuan, 24 sheets for 5 yuan and 24 sheets for 10 yuan

1. Find out the rules and fill in the blanks: (1) 3,9,11,17,20, -, -, 36,41
（2）1,3,2,6,4,— ,—,12,16.

1、
3,9,11,17,20,(26),(30),36,41
Odd and even numbers are 8, 9 and 10 increasing
2. The singular digits are 1, 2, 4, 8 and 16, which are the equal ratio sequence of 2
The double digits are 3, 6, 9 and 12, which are the arithmetic sequence of 3
（2）1,3,2,6,4,9,8,12,16.

(m2-8m + 17) x2 + 2mx + 1 = 0 finding the value of m makes the equation have two equal real roots

(m ^ 2-8m + 17) x ^ 2 + 2mx + 1 = 0 has two equal real roots
And m ^ 2-8m + 17 = (M-4) ^ 2 + 1 ≠ 0
So Δ = 4m ^ 2-4 (m ^ 2-8m + 17) = 0
So m = 17 / 8
If you don't understand, please hi me, I wish you a happy study!

(x * arctan (x)) / (1 + x ^ 2) ^ 2, integral

(x * arctan (x)) / (1 + x ^ 2) ^ 2, integral
=(x + (-1 + x^2) ArcTan[x])/(4 (1 + x^2))+c

Fill in the numbers (1, 7, 13, 19, 25, ···, N, (), ()) according to the rules. It's super urgent. It's done now! I need it now. Quick, urgent

n+6,n+12

The two integers adjacent to the natural number n are (n + 1) and (n-1) respectively, and the sum of these three numbers is ()

3n