Each pencil is 0.9 yuan, 2 yuan, 3 yuan, 4 yuan, 5 yuan. Which pencil is cheaper? The number of people who want to score is limited, only one, and those who want to score will come quickly

Each pencil is 0.9 yuan, 2 yuan, 3 yuan, 4 yuan, 5 yuan. Which pencil is cheaper? The number of people who want to score is limited, only one, and those who want to score will come quickly

zero point nine
2/3=0.66666667
4/5=0.8
Two yuan and three pencils are cheaper

It costs 4 yuan and 7 Jiao to buy 4 erasers and 3 pencils. It costs 2 yuan and 1 jiao to buy the same 2 erasers and 1 pencil. How much do you charge for each eraser and 1 pencil

1
2 erasers and 1 pencil is 2.1 yuan, 4 pencils 2 erasers is 4.2 yuan, 4 erasers 3 pencils is 4.7 yuan. A pencil is 4.7-4.2 = 0.5 yuan. An eraser is (2.1-0.5) / 2 = 0.8 yuan
2. Use the equation. Suppose a rubber X Yuan and a pencil y yuan. According to the equations bought by two people
4X+3Y=4.7
2X+Y=2.1
Just solve the equation

What primes are 30 made of?
As shown in the figure: 30 = () + () = () + () = () + ()

30=2×3×5
30=7+23
=11+19
=13+17

Given the function f (x) = loga (3-ax); (1) when x ∈ [0,2], the function f (x) is always meaningful and the value range of real number a is obtained; (2) is there such a real number a that the function f (x) is a decreasing function in the interval [1,2] and the maximum value is 1? If there is, try to find the value of a; if not, explain the reason

(1) Let 3-ax ＞ 0 hold for all x ∈ [0,2], a ＞ 0 and a ≠ 1 (2 points) ∵ a ∵ 0, ∵ g (x) = 3-ax is a decreasing function on [0,2] (4 points) so g (2) = 3-2a ＞ 0, a ＜ 32, the value range of a is (0,1) ∪ (1,32) (6 points) (2) suppose that there is such a real number a, Let f (1) = 1, that is, loga (3-A) = 1, a = 32, then f (x) = log32 (3 − 32x) When x = 2, f (x) has no meaning, so such a real number does not exist (12 points)

We know the function f (x) = log2x1 − X. (I) find the domain of the function; (II) according to the definition of monotonicity, we prove that the function f (x) is an increasing function

(I) from & nbsp; x1 − x ＞ 0 to & nbsp; X (1-x) ＞ 0, the solution shows that & nbsp; 0 ＜ x ＜ 1, and the domain of definition of function is & nbsp; (0,1). (II) it is proved that if x1, X2 ∈ (0,1) and x1 ＜ X2, then f (x1) − f (x2) = log2x11 − x1 − log2x21 − x2 = log2 (X11 − x1 · 1 − x2)

Imitative ABC + CBA = EFG EFG + GFE = XYZ XYZ + ZYX = palindrome number

The code is as follows: # include # include using namespace STD; int trans (int x) {int CICI = 0; CICI = CICI * 10 + X% 10; X / = 10; CICI

Let the probability density of two-dimensional random variable (x, y) be f (x, y) = 12Y ^ 2,0

EX=∫∫[0

Matlab Rands how to use this function, the best example

Use of rand (s, PR),
S - number of neurons
The input range of PR - rx2 matrix R
Returns an s * r weight matrix with random values between - 1 and 1

Integral multiplication______ 、______ And______ The same is true for fractional multiplication

Commutative law, associative law and distributive law of integer multiplication are also applicable to fractional multiplication

A parallelogram and a triangle have the same base and height. It is known that the area of a parallelogram is 36 square centimeters. What is the area of a triangle

18 square centimeters
The area of the triangle is 1 / 2 ah
The area of a parallelogram is ah