The range of function y = (AX ^ 2 + 8x + b) / (x ^ 2 + 1) is {y | 1 ≤ y ≤ 9}. Find the value of a and B

The range of function y = (AX ^ 2 + 8x + b) / (x ^ 2 + 1) is {y | 1 ≤ y ≤ 9}. Find the value of a and B

Let's look at the problem of the discriminant (1) (AX ^ 2 + 8x + b) / (x ^ 2 + 1) > = 1 constant (AX ^ 2 + 8x + b > = x ^ 2 + 1 constant (A-1) x ^ 2 + 8x + B-1 > = 0 constant, so A-1 > 0 and the discriminant is equal to zero (because y can take 1) discriminant = 64-4 (A-1) (B-1) = 0. (1) (II)

The range of the function y = LG (x + 1) is
a. (0, positive infinity) B, (negative infinity, positive infinity) C, (negative infinity, 0) d (0,1)

b
As long as the true number can take all positive real numbers, the logarithm can take all real numbers

What is the sum of all natural numbers in a column of natural numbers 1,2,3.999?

(1+999)*999/2
=499500

It is known that the speed of a bus is 80 km / h, and the speed of a truck is 3 / 4 of that of a bus. How many hours can a bus and a truck meet each other?

210 △ (80 + 80 × 3 / 4)
=210÷140
=1.5 (hours)

Cube of (x + 2) - (X-2)

Cube of (x + 2) - (X-2)
=X³+6x²+12x+8-(x³-6x²+12x-8)
=X³+6x²+12x+8-x³+6x²-12x+8)
=12x²+16
=4(3x²+4)

x+3/5x=2/25

It's two fifths

If the height of a cylinder block is reduced by 2 cm, the surface area will be reduced by 12.56 square cm, which is the same as that of the original cylinder

S side = l circumference XH
According to the meaning of the title,
L circumference X100 = l circumference x98 + 12.56
2L circumference = 12.56
L circumference = 6.28
Therefore, we can get s side = l circumference XH = 6.28x100 = 628 square centimeter
L circumference = 2 μ r = 6.28 (take μ = 3.14)
Then r = 2
Then s-bottom = 5 RXR = 3.14x2x2 = 12.56
S Cylinder = 2S bottom surface + s side = 2x12.56 + 628 = 653.12 square centimeter

The sum of 10 different natural numbers is 2002. What is the maximum common divisor of them?

To see their greatest common divisor, just look at the divisor of 2002
The divisors of 2002 are 1, 2, 7, 11, 13, 14, 22, 26, 77, 91, 143, 154, 182, 286, 1001, 2002
Now 2002 = the sum of 10 natural numbers = the greatest common divisor × (the sum of 10 numbers divided by the greatest common divisor), the number in brackets must be a positive integer, and also the sum of 10 other different natural numbers, so its minimum value is 55 (i.e. 1 added to 10)
2002 △ 55 = 36.4, that is, the common divisor must be less than 36.4
So the greatest common divisor can be 26

In a triangle, triangle a, B and C are arithmetic sequences, and the corresponding sides are a, B and C. proof: 1 / (a + b) + 1 / (B + C) = 3 / (a + B + C) it seems that direct proof or indirect proof is the most important way for elder brother and elder sister to help younger brother

Using B = 60 degree
Cosine theorem B = you know
Then the equation is divided on both sides
The indirect proof is to change ABC into Sina sin B sin C
Let a = 60 ° - x, C = 60 ° + X and then substitute it into the expansion

Summer homework is not finished, school is about to start. How to do? There are still 10 days to teach me a lot of homework online
I don't have to ask if I can copy the answers myself``
I don't want to copy homework in senior three, but I can't write it myself. How can I do it? It's a miserable summer vacation in senior two. Copying homework is the bottom line. Now I want a way to force myself to finish it, If the method is too common, I won't come to this expert so many places to ask XD first! Thank you first! There's no need to increase the reward. If there's a good method, I'll offer a reward again. I don't want those points``