The perimeter of a rectangle is 22.6 cm. After it is divided into two rectangles, the sum of the perimeter is 16 cm larger than the original rectangle, which is the area of the original rectangle What's the square centimeter?

Let the original rectangle be a in length and B in width
2(a+b)=22.6 a+b=11.3
2a=16 a=8
b=11.3-8=3.3
The area of the original rectangle: S = AB = 8 * 3.3 = 26.4cm & # 178;

Find the limit of X / SiNx when x tends to 0
The limit of SiNx / X is 1. When x tends to 0, how much is the reverse? It's best to give a proof

It's all 1
When x tends to zero, SiNx and X are equivalent infinitesimals

It is known that the ellipse C and the ellipse x2 / 4 + Y2 / 9 = 1 have the same focus, and the ellipse C passes through the points (2, - 3). The standard equation of the ellipse C is obtained

c^2=5
a^2=5+b^2
2^2/b^2+(-3)^2/(5+b^2)=1
b^2=10,a^2=15
x^2/10+y^2/15=1

If an integer has the following properties: (1) the difference between this number and 1 is a prime number; (2) the quotient of this number divided by 2 is also a prime number; (3) the remainder of this number divided by 9 is 5. We call this integer a lucky number?

The multiples of 9 within 100 are: 9, 18, 27, 36, 45, 54, 63, 72, 80, 81, 90, 99. The remainder of (3) divided by 9 is 5:14, 23, 32, 41, 50, 59, 68, 77, 86, 95. The difference between (1) and 1 is prime. The quotient of (2) divided by 2 is prime

The increase and decrease of quadratic function f (x) = AX2 + BX + C (a < 0) in the interval [- B2A, + ∞) is judged and proved according to the definition

Let x1, X2 ∈ [- B2A, + ∞) and X1 < X2, then f (x1) - f (x2) = a (x12-x22) + B (x1-x2) = a (x1-x2) (x1 + x2 + BA), ∵ x1, X2 ∈ [- B2A, + ∞) - BA < X1 + x2 < + ∞ X1 + x2 + Ba > 0, and x1-x2 < 0, a < 0

Given the function f (x) = LG [(A2-1) x2 + (a + 1) x + 1] (1) if the domain of F (x) is r, find the value range of real number a; (2) if the domain of F (x) is r, find the value range of real number a

(1) When A2-1 = 0, a = - 1, a = 1 does not hold. When A2-1 ≠ 0, A2 − 1 ＞ 0 △ = (a + 1) 2 − 4 (A2 − 1) ＜ 0, a ＞ 53 or a ＜ - 1 is obtained. In conclusion, a ＞ 53 or a ＜ - 1 (2) when A2-1 = 0, a = 1, a = - 1 does not hold

If a prime number is prime after adding 6, 8, 12 and 14, then the prime number is______ ．

Let this prime number be x, divide X by 5, and divide the remainder into the following five cases: when x = 5K + 1, then x + 14 = 5 (K + 3) is a composite number, when x = 5K + 2, then x + 8 = 5 (K + 2) is a composite number, when x = 5K + 3, then x + 12 = 5 (K + 3) is a composite number, when x = 5K + 4, then x + 6 = 5 (K + 2) is a composite number, so only x = 5K and K is 1, that is x = 5

Let's see if there is a problem with this marginal density function
f(x,y)=4.8y(2-x） 0≤x≤1
0 others
Find the edge probability density FY (y)
I feel that there is something wrong with the range of X and y
0≤x≤1 1≤y≤x
Let's leave aside the question of scope, but there are answers in the book,
It's about probability

How can there be 0 ≤ x ≤ 1 ≤ y ≤ x?
The problem of edge density is a double integral. For example, the edge density of Y is the integral of X from negative infinity to positive infinity, and then the integral of Y from negative infinity to y. if 0 ≤ x ≤ 1, the integral range of X becomes from 0 to 1, because the integrals in other places are all 0. This is a problem of applying formulas

The function y = asinx + B has a maximum of 3 and a minimum of 2
Ask for detailed explanation

sinx∈[-1,1]
1
{a+b=3
{-a+b=2
The solution is: a = 0.5, B = 2.5
2
{a+b=2
{-a+b=3
The solution is: a = - 0.5, B = 2.5

The perimeter of a rectangle is 22.6 cm. After it is divided into two rectangles, the sum of the perimeter is 16 cm larger than the original rectangle, which is the area of the original rectangle What's the square centimeter?