The substitution method is used to solve the equations: one third x + y + two thirds X-Y = 63 (x + y) - 2 (X-Y) = 28 The substitution method is used to solve the equations: one third x + y + two thirds X-Y = 63 (x + y) - 2 (X-Y) = 28

The substitution method is used to solve the equations: one third x + y + two thirds X-Y = 63 (x + y) - 2 (X-Y) = 28 The substitution method is used to solve the equations: one third x + y + two thirds X-Y = 63 (x + y) - 2 (X-Y) = 28

The equations 0.2x-0.5y = 0.5 (x-1) - 3 (y + 17) = 0 are solved by substitution elimination method

Move 0.5y to the right of the equal sign, and substitute the first one into the elimination to make x = 2.5Y,
Substituting the second formula 5 (2.5y-1) - 3 (y + 17) = 0,
It is reduced to y = 112 / 19,
Then x = 2.5Y = 280 / 19

Solving the equations {3 (Y-2) = x + 1,2 (x-1) = 5y-8

3(y-2)=x+1
2(x-1)=5y-8
The results are as follows
3y-x=7 ①
2x-5y=-6 ②
① X 2 + 2 = y = 8
Substituting into the solution: x = 17
Therefore, the solution of the equations is:
x=17
y=8

1. How many polynomials are there if a monomial containing both the letters X and y has a coefficient of 1 and a degree of 5?
2. XiaoCong bought m notebooks with a unit price of X Yuan and N notebooks with a unit price of Y yuan, then the average price of these notebooks is?
3. A binomial of degree 5 with X and y, the exponent of X is 3, and when x = - 2, y = 1, the value of this binomial is - 40, so how to find this binomial?

There are four such polynomials
2. Average price = (XM + yn) / (M + n)
3.-5x^3y2

Is a single number and letter a monomial? If so, what are their coefficients and times?
Prawns, help

Yes, this is the original words on page 55 of the first volume mathematics book of junior high school
If it is a single letter, the coefficient is 1 and the number is 1
The number coefficient is itself times zero
If you don't know, ask again^_^

Write a monomial with only letters A and B, coefficient - 2 and degree 4
I think it's very strange that there can only be a and B, how can there be - 2? Then there is not only a and B, but also a - 2?

-2ab^3
-2 is the coefficient

Mathematics review, algebraic concept
1. Note: when using letters to express numbers:
① When a letter is multiplied by a number or letter, the multiplication sign can be omitted
② Multiplication of letters and numbers______ Write in front of the letter
③ The sum of the following units______
④ Division is written as______ The form of
⑤ When multiplying a letter with a fraction, write______
2. Algebraic formula: the algebraic formula consists of____________ And operational symbols, separate______ It's also an algebraic expression____________ .
3. The value of an algebraic expression: generally______ The result of the calculation is called the value of the algebraic expression
4. Monomials: by____________ A formula is called a monomial______ Also called monomials
5. The coefficient of a monomial______ It's called the coefficient of the monomial
6. The times of a monomial: in a monomial______ It's called the number of monomials
7. Polynomial:____________ The algebraic form of a composition is called a polynomial
8. Terms of Polynomials: in polynomials, each______ A term called a polynomial______ It's called a constant term
9. Degree of Polynomials: in Polynomials____________ This is the degree of this polynomial
10. Integral:____________ They are called integers
11. In polynomials__________________ The term of the same kind is called the term of the same kind
12. The rule of merging similar items:____________ As a coefficient____________ unchanged.
13. Rule of removing brackets: the "+" sign is before the brackets__________________ ；
Before the brackets is a sign__________________ .

Numbers
Units should be unified
fraction
Fraction form
2. Number and letter number or letter algebra operation
3,

Two elementary three Algebras
1. It is known that when x = - 2, the value of the algebraic formula ax ^ 3 + BX + 1 is 6. When x = 2, the value of the algebraic formula ax ^ 3 + BX + 1 is obtained
2. Given x ^ 2 + X-1 = 0, find the value of the algebraic formula x ^ 3 + 2x ^ 2-7

1. When x = - 2, a (- 2) ^ 3 + (- 2) B + 1 = 6
-2^3a-2b+1=6
So - 2 ^ 3a-2b = 5
SO 2 ^ 3A + 2B = - 5
When x = 2, ax ^ 3 + BX + 1 = 2 ^ 3A + 2B + 1 = - 5 + 1 = - 4
2. X (x + 1) = 1 from x ^ 2 + X-1 = 0
X^3+2x^2-7=X^3+x^2+x^2-7=x^2(x+1)+x^2-7=x.x(x+1)+x^2-7=x+x^2-7=1-7=-6

On all knowledge points of algebraic expression

The product of letters or numbers is a monomial, such as: 2A, a single number is also a monomial, because for example: 5 = 5 (a ^ 0) (where a ≠ 0). This is the concept of a monomial. Polynomial is simply the sum of several monomials, such as 2A + 3b-6c (where minus 6C is regarded as plus -...)

Algebraic expressions
Given x ^ - 4xy + y ^ = 0. Find the value of X / y

Divide y ^ 2 on both sides of the equation
Then: (x / y) ^ 2-4 (x / y) + 1 = 0;
(x / y) = 2 plus minus root 3