1. Chicken 3 yuan, egg 2 yuan, give you 100 yuan, how many ways to buy, but also know the meaning of it

1. Chicken 3 yuan, egg 2 yuan, give you 100 yuan, how many ways to buy, but also know the meaning of it

17 species ～
Let x eggs and Y chickens, then 2x + 3Y = 100
X = 2, y = 32; X = 5, y = 30. Each x corresponds to a Y ~ X. The maximum is 50, from 2 to 50, and the tolerance is 3,
((50-2) / 3) + 1 has 17 positive integers, so there are 17 Ways to buy

Decomposition factor - 4m minus 4m minus n

Do you want to type N less?
-4mn-4m^2-n^2
=-(4m^2+4mn+n^2)
=-(2m+n)^2

(- 24) * (1 / 2 + 1 / 3-1 / 4-7 / 12) / (- 1 and 1 / 5)

(- 24) * (1 / 2 + 1 / 3-1 / 4-7 / 12) / (- 1 / 5) = (- 24) * (1 / 2 + 1 / 3-1 / 4-7 / 12) x (- 5 / 6)
=20x（1/2+1/3-1/4-7/12）
=10+20/3-5-35/3
=5-5
=0

A cylindrical steel is 1m long. Cut it into two sections, and the surface area is 100.48 square centimeters larger than the original. What is the original volume and surface area of this steel?

First of all, let the children understand that the cylindrical steel is cut into two sections, which generally means that the height or length is divided into two sections, so the increased area is the two bottom surfaces of the cylinder. Then each surface is 100.48 △ 2 = 50.24 (square centimeter), so the original volume is: 1m = 100cm; 50.24 × 100 = 5024 (square centimeter), Base area = circumference × radius × radius; 50.24 △ 3.14 = 16 (CM) 16 = 4 × 4; so radius is 4cm; side area: 2 × 3.14 × 4 × 100 = 2512 (cm2), surface area: 100.48 + 2512 = 2612.48 (cm2)

A two digit number, minus three times the sum of its digits, results in 23. The quotient of this two digit number divided by the sum of its digits is 5, and the remainder is 1. What are these two digits?

Let X be the ten digit number of this two digit number, and y be the number of each digit. According to the meaning of the question, we get 10x + y − 3 (x + y) = 2310 x + y = 5 (x + y) + 1, and the solution is x = 5Y = 6, so this two digit number is 56. A: this two digit number is 56

A piece of annular paperboard has an outer perimeter of 12.56 decimeters and an inner perimeter of 9.42 decimeters. What is the area of the annular paperboard

Outer radius: 12.56 △ 3.142 = 2
Inner radius: 9.42 △ 3.14 △ 2 = 1.5
Area: (2 × 2-1.5 × 1.5) × 3.14 = 5.495 square decimeters

（1*6*9+2*12*18+3*16*27+...+100*600*900）÷（1*2*3+2*4*6+3*6*9+...+100*200*3

（1*6*9+2*12*18+3*16*27+...+100*600*900）÷（1*2*3+2*4*6+3*6*9+...+100*200*300）=[1*6*9(1+2^3+3^3+4^3+.+100^3)]/[1*2*3(1+2^3+3^3+4^3+.+100^3)]=9

Square of (a + 2b) - square of 4B

There are three different numbers, which can make up six different three digit numbers. The sum of them is 3330?

Answer: 159 let these three numbers be a, B and C respectively. According to the permutation and combination principle, these three numbers can be arranged into six three digit numbers only when they are different, and they appear twice in the hundreds, tens and individual digits of the three digit numbers, a, B and C respectively. Therefore, there is an equation: (100 + 10 + 1) (2a + 2B + 2C) = 3330, so after a + B + C = 15, because a

Solving the quadratic equation of two variables
{7x-3y=-1
{4x-5y=-17

7x-3y=-1 (1）
4x-5y=-17 （2）
(1)*5,35x-15y=-5
(2)*3,12x-15y=-51
subtract
23x=46
x=2
Bring in (1)
14-3y=-1
y=5