What mathematical problems can be solved with 45 △ in the third grade of primary school

What mathematical problems can be solved with 45 △ in the third grade of primary school

Can solve the problem is you bought 5 or more things, a total of 45 yuan, the average how much each

4x-5y = 0, (x, y are not equal to 0), is x proportional to y? If so, what is the proportion
If you can, please analyze

4X = 5Y, so it is proportional, the coefficient remains unchanged, and Y becomes larger and smaller with the increase of X

The application of the first degree equation of one variable in elementary school
I'm not very good at the application of one variable linear equation in grade one of junior high school. Our monitor, practice makes perfect, and will soon be able to list the relevant equations according to the meaning of the topic. I can't do it. If I want to list the equations, I have to find the same quantity first, so I have a headache. I think this equation is very complicated. The equations are also wrong
How on earth can we better understand the meaning of the question and list the correct equations? I'm so anxious. This is the key point! Let's talk about the specific process

It is much easier to solve practical problems by using equations than by using hard methods in primary schools. However, because of the first contact with equations, junior high school students generally feel difficult to solve practical problems by using equations

(1) Let the coefficient of the X term be 1, which is the coefficient of the unknowns on both sides of the equation
(2) If 2x6 ^ M-1 + 3M = 1 is a linear equation of one variable with respect to x, then M = ()
One question is OK,

(1) Making the coefficient of the term x 1 is based on the coefficient of the unknowns on both sides of the equation
(2) If 2x ^ M-1 + 3M = 1 is a linear equation of one variable with respect to x, then M = (1)
If 2x ^ (m-1) + 3M = 1 is a linear equation of one variable with respect to x, then M = (2)

16x & # 178; y-16x & # 179; - 4xy factorization

16x²y-16x³-4xy
=4x(4xy-4x²-y)

If 10A & # 178; (a-b) & # 178; - 5A (B-A) & # 179; = m (3a-b), then M=

If 10A & # 178; (a-b) & # 178; - 5A (B-A) & # 179; = m (3a-b)
=5a（a-b）²(2a+a-b)
=5a(a-b)(3a-b);
Then M = 5A (a-b);
If you don't understand this question, you can ask,

Find the maximum and minimum of the function f (x) = cos ^ 2x - √ 3sinxcosx

f(x)=cos^2x-√3sinxcosx=1/2+﹙cos2x﹚/2－√3/2sin2x=1/2+sin(π/6-2x)
∵-1≤sin(π/6-2x)≤1
∴-1/2≤f(x)≤3/2
The maximum value is 3 / 2 and the minimum value is - 1 / 2

As shown in the figure, the parabola Y1 = a (x + 2) 2-3 and y2 = 12 (x-3) 2 + 1 intersect at point a (1,3), cross point a as a parallel line of X axis, and intersect two parabola at points B and C respectively. Then the following conclusions are drawn: ① no matter what value x takes, the value of Y2 is always positive; ② a = 1; ③ when x = 0, y2-y1 = 4; ④ 2Ab = 3aC; where the correct conclusion is ()
A. ①②B. ②③C. ③④D. ①④

① ∵ the parabola y2 = 12 (x-3) 2 + 1 has an opening upward, and the vertex coordinates are above the x-axis. No matter what the value of X is, the value of Y2 is always positive, so this problem is correct. ② substituting a (1,3), the parabola Y1 = a (x + 2) 2-3, 3 = a (1 + 2) 2-3, a = 23, so this problem is wrong

For any rational number x.y.z. x * x = 0, X * (y * z) = (x * y) + Z, then the value of 2008 * 5 is
kkkkkkkkk

x*(y*z)=(x*y)+z
Let y = Z have X * (y * y) = (x * y) + y
x*0=(x*y)+y……………… one
x*y=x*0-y……………… two
Substituting x = 2008, y = 5 into formula 2, there is 2008 * 5 = 2008 * 0-5 three
Then put x = 2008, y = 2008 into Formula 1, there is 2008 * 0 = 2008, put this formula into formula 3, get 2008 * 5 = 2003

2x+56+4x=92 (5+x)*8=104 2x+7x=108

2x+56+4x=92
6x=92-56
6x=36
x=6
(5+x)*8=104
5+x=13
x=8
2x+7x=108
9x=108
x=12