(- x ^ 2 + 8 + 5x ^ 3) + (- 2x ^ 3 + 5x-7) where x = - 2

(- x ^ 2 + 8 + 5x ^ 3) + (- 2x ^ 3 + 5x-7) where x = - 2

(-x^2+8+5x^3)+(-2x^3+5x-7)
=3x^3-x^2+5x+1
=3x(-2)^3-(-2)^2+5x(-2)+1
=-24-4-10+1
=-37
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As shown in the figure, the height of a cylinder is 8 cm. If its height is increased by 2 cm, its surface area will increase by 25.12 square cm. The volume of the original cylinder is 2 cm______ Cubic centimeter

The radius of the bottom circle of the cylinder: 25.12 △ 2 △ 3.14 △ 2 = 2 (CM); the volume of the original cylinder: 3.14 × 22 × 8 = 100.48 (cm3); answer: the volume of the original cylinder is 100.48 cm3. So the answer is: 100.48

It is known that a * 1 and 2 / 3 = b * 90% = C / 75% = D * 4 / 5 = E / 1 and 1 / 5

A

If the function f (x) = x ^ 2-bx + 2 has an inverse function on the closed interval [- 1,2], then the range of real number B?
If the function f (x) = ax ^ 2 + BX + 6 satisfies the condition f (- 1) = f (3), then the value of F (2) is?
If f (x) = (m-1) x ^ 2 + 2mx + 3 is an even function, then why is f (x) an increasing function in the interval (- 5, - 2)?
Let (x ≤ 0) f (x) = x ^ 2 + BX + C, if (x > 0) f (x) = 2, if f (- 4) = f (0), f (- 2) = - 2, then the number of solutions of the equation f (x) = x about X is?
Given that the function y = x ^ 2-2x + 3 has a maximum value of 3 and a minimum value of 2 in the closed interval [0, M], then the value range of M is
[ 1,2]
If the function f (x) = (m-1) x ^ 2 + 2 (M + 1) X-1 image has only one intersection with the X axis, then the value set of the real number m is?

1. Two monotone intervals (negative infinity, B / 2) and (B / 2, positive infinity) of F (x); [- 1,2] must be in one of them, that is, 2 = B / 2;
2. The axis of symmetry is x = - B / (2a) = (- 1 + 3) / 2, B = 2A, so f (2) = 6;
3. The definition of even function can get m = 0, so f (x) increases at (negative infinity, 0) and decreases at (positive infinity, 0);
4. If x = - B / 2 = (- 4 + 0) / 2, B = 4, f (- 2) = - 4 + C = - 2, C = 2;
If (x0) f (x) - x = 2-x = 0, a positive root
There are three solutions
5. The range of Y is [2, positive infinity), so [0, M] must include the axis of symmetry x = 1,
When y = 3, x = 0 or 2, so 2 > = m > = 1,
6. If f (x) is a quadratic function (i.e. M-1 ≠ 0), then Δ = 0 = 4m (M + 3), then M = 0 or - 3;
When f (x) is a straight line (i.e. M-1 = 0), because it is not parallel to the X axis, there must be an intersection,
So m belongs to {- 3,0,1}

A cage contains chickens and rabbits. There are 88 counting heads and 234 counting feet. How many chickens and rabbits each
Don't list English letters

Look at the rabbit as two feet
88*2=176
234-176=58
The 58 extra feet are the number of feet left after the rabbit sees two feet
58 / 2 = 29, which is the number of rabbits
88-29 = 59, which is the number of chickens

Let XY be two numbers, X * y = x of Y-X of Y, 18 * 3-1 / 3

18*3-1/3
=18/3-3/18-1/3
=6-1/6-1/3
=6-1/2
=5.5

There are 70 numbers. Three times of each number minus the previous number equals to the next number. How many is the last number on the right divided by six? The first numbers are 0,1,3,8,21,55

How much is the rightmost number (the 70th number) divided by 6?
First of all, notice that from the third number, each number is exactly equal to three times of the previous number minus the previous number
3＝1×3-0,
8=3×3-1,
21=8×3-3,
55=21×3-8,
……
However, it's too troublesome to calculate one by one and then get rid of 6 one by one. Can we calculate the remainder from the previous remainder? Yes, it's the same way to calculate the number in this line (why?). Starting from the third number, we can calculate the remainder as follows:
Multiply the remainder of the previous number by 3, subtract the remainder of the previous number, and then divide by 6
With this method, the remainder can be calculated one by one. The list is as follows:
Note that when we calculate the remainder of the eighth number, we need to have 0 × 3-1, which is not allowed in primary school mathematics, because we can find the remainder divided by 6, so we can add 0 × 3 and 6 and then subtract 1
It can be seen from the table that the remainder of the thirteenth and fourteenth numbers correspond to the same number as the remainder of the first and second numbers, so we know that the cycle period of the remainder is 12
70 ＝12×5+10.
Therefore, the remainder of the 70th number divided by 6 is the same as the remainder of the 10th number, that is, 4
Saw a related example, had to answer by oneself

When the values of X and Y increase to two times of the original, the values of the following formulas change ()
A. Y / x + y b.x-y / x + y c.x square + y square / x + y D.X square + y square / x square - y square

A will not change, the result will not change
The same goes for B
C can be divided into X-Y, so it will be twice the original. Choose C

It takes 7.5 hours for a middle school to plant trees outside the school. It takes 5 hours for the eighth grade students to plant trees alone. Now let the seventh and eighth grade students plant trees together for one hour, and then let the eighth grade students complete the rest. How many hours do it take?

Suppose that it takes x hours to complete, from the meaning of the question, 17.5 + 15x = 1, the solution is: x = 413

Please write an algebraic formula containing the letter X, so that when x = a or x = 1 / A, the values of the algebraic formula obtained are equal. Why is it x + 1 / x? It's wrong to substitute it

X+1/X
x=a
X+1/X=a+1/a
x=1/a
X+1/X=1/a+1/(1/a)=1/a +a=a+1/a
The two are equal