Given the equation 2x + 3Y = 7, we use the formula containing y to express that x is

Given the equation 2x + 3Y = 7, we use the formula containing y to express that x is

Given the equation 2x + 3Y = 7, we use the formula containing y to express that x is
3y=7-2x
y=（7-2x）÷3
Y = 3 / 3 (7-2x)

Summary of mathematics knowledge points of grade seven published by China Normal University
I hope there is a more accurate answer,

Mathematics knowledge of grade seven
Chapter one into the world of Mathematics
Chapter two rational numbers
1. Number axis: three elements of the number axis: origin, positive direction and unit length; the points on the number axis correspond to real numbers one by one
2. The opposite number of the opposite number real number a is - A; if a and B are opposite to each other, then a + B = 0, and vice versa; geometric meaning: on the number axis, two points representing the opposite number are located on both sides of the origin, and the distance to the origin is equal
3. Reciprocal: if the product of two numbers is equal to 1, then the two numbers are reciprocal to each other
4. Absolute value: algebraic meaning: the absolute value of a positive number is itself, the absolute value of a negative number is its opposite number, and the absolute value of 0 is 0; geometric meaning: the absolute value of a number is the distance from the point of the number to the origin on the number axis
5. Scientific notation: where. 6. Comparison of real number size: comparison of size by law; comparison of size by number axis
7. In the range of real number, addition, subtraction, multiplication, division and power operation can be carried out, but square root operation is not necessarily feasible, such as negative number can not open even power. The basis of real number operation is rational number operation, and all operation properties and operation laws of rational number are applicable to real number operation. Correct determination of operation result symbols and flexible use of operation laws are the keys to master real number operation
Chapter 3 addition and subtraction of integral
1、 Some concepts of integral
1. Monomial: the product of numbers and letters. Such an algebraic formula is called a monomial. A single number or letter is also a monomial
2. Coefficient of a monomial: the numerical factor in a monomial
3. The number of monomials: the exponential sum of all the letters in a monomial
4. Polynomial: the sum of several monomials is called polynomial
5. Term and degree of polynomial: the monomial in a polynomial is called the term of a polynomial, and the degree of the item with the highest degree in a polynomial is called the degree of a polynomial. In particular, the degree of a polynomial is not the sum of all the letter indices of a polynomial!
6. Integers: monomials and polynomials are collectively called integers
2、 Operation of integral
（1） The basic steps of integral addition and subtraction: remove brackets and merge similar items
（2） Multiplication of integers
1. Multiplication rule of power with the same base number: multiply the power with the same base number, keep the base number unchanged and add exponentially___ (where m and N are positive integers)
2. The law of power: the power of the power, the base unchanged, exponentially multiplied_______ (where m and N are positive integers)
3. The law of product's power: in the power of product, the factors in the product are multiplied separately, and then the resulting powers are multiplied. (that is, the product of the power of the factors in the product_______ (where n is a positive integer)
4. The law of power division of the same base number: the power of the same base number is divided, the base number remains unchanged, and the exponent is subtracted___ (where m and N are positive integers)
5. The law of the multiplication of a monomial by a monomial: when a monomial is multiplied by a monomial, its coefficient and the power of the same letter are multiplied respectively, and the rest of the letters, together with its exponent, remain unchanged as a factor of the product
6. The law of multiplication of a polynomial by a monomial: multiplication of a polynomial by a monomial is to multiply each term of a polynomial according to the law of distribution, and then add up the products
7. The rule of multiplying polynomials by Polynomials: multiply polynomials by polynomials, multiply each term of one polynomial by each term of another, and then add the products
8. Square difference formula rule: each of two numbers multiplied by the difference of the two numbers is equal to the square difference of the two numbers_____ (where a and B can be numbers or algebraic expressions) Note: the square difference formula is obtained by multiplying a polynomial by a polynomial, which is the product of the sum of two numbers and the difference of the same two numbers
9. The rule of complete square formula: the square of the sum (or difference) of two numbers is equal to twice the sum of the squares of the two numbers plus (or minus) the product of the two numbers
The mathematical symbol indicates:______
（2） Division of integers
1. The rule of monomial divided by monomial: a monomial divided by a monomial, their coefficients and the powers of the same letters are divided respectively, and then they are regarded as a factor of quotient. For the letters only contained in the division, they are regarded as a factor of quotient together with their index
2. Polynomials divided by monomials rule: polynomials divided by monomials, that is, each term of polynomials is removed by monomials, and then the quotient is added
The fourth chapter is a preliminary understanding of graphics
1. Point, line and surface: further understand the point, line and surface through abundant examples (for example, the city is represented by points on the traffic map, and the screen is composed of points). 2. Angle: 1. Further understand the angle through abundant examples. 2. Compare the size of the angle, estimate the size of the angle, calculate the sum and difference of the angle, and identify the degree, minute and second, Can carry on the simple conversion. ③ understands the angle bisector and its nature
Intersecting and parallel lines
1、 Basic concepts
1. Straight line: (1) a straight line is a straight line__________ (2) there is only one line passing through two points__________ .
Ray: a point on a straight line and the part beside it is called a ray__________ This point is called the end point of the ray. The ray has only one end point
2. Line segment: (1) the part between two points on a straight line is called line segment__________ ,__________ There are two endpoints__________ The shortest
(3) The point where a line segment is divided into two equal lines is called the point of the line segment__________ .
When two straight lines intersect, one of the four corners is vertical__________ It is called that two lines are perpendicular to each other; one line is called the vertical line of the other line, and their intersection is called the vertical line of the other line__________ .
5. The properties of perpendicular: (1) passing through a point, there are and only___ (2) in all line segments connected by a point outside the line and each point on the line__ The shortest
6. Distance between two points: connection__________ The length of the line segment
7. Distance from point to line: from a point outside the line to__________ The length of the vertical segment of the
8. Distance between two parallel lines: on one of the two parallel lines__________ The distance to another straight line
9. Corner: two points with common end__________ The common end point is called the vertex of the angle, and these two lines_____ It's called the edge of the corner
10. Angle bisector: starting from the apex of an angle, divide the angle into two parts__________ The ray of an angle is called an angular bisector
11. Horizontal angle and perimeter angle: the ray rotates around the end point, when the ending position and the starting position are in a linear relationship__________ The angle formed is called a flat angle; continue to rotate back__________ Position, the angle is called the circumference
12. Angle measurement: 1 circle angle =__ Flat angle =___ Right angle = 360 degree, 1 degree = ' , 1’=___”
13. Classification of angles smaller than horizontal angle:__________ Angle__________ Angle__________ Angle
14. Complementary angle: if the sum of two angles is_ If the sum of the two angles is_ These two angles are called complementary angles
15. Properties of correlation angle: (1) for vertex angle______ (2) Congruent or equiangular angles_____ (3) complementary angle of the same angle or equal angle_______ .
2、 Intersecting and parallel lines
1. Parallel line: in the same plane__________ The two straight lines are called parallel lines
2. In the same plane, there are only two kinds of positional relations between two straight lines__________ When intersecting, the opposite vertex angles are equal
3. The judgment of parallel line: (1) the same position angle___ (2) if the internal angle is equal, the two lines are parallel_____ .
(3) Ipsilateral angle__________ (4) two lines parallel (or perpendicular) to the same line__________ .
4. The properties of parallel line: (1) passing through a point outside the line, there are and only____ A straight line is parallel to this one
(2) The two lines are parallel and at the same angle_______ (3) the two straight lines are parallel, and the internal angle is staggered__________ .
(4) The two lines are parallel and have the same inner angle_ (5) a straight line is perpendicular (or parallel) to one of two parallel lines, and this straight line is also perpendicular to the other_ Vertical (or parallel)
(6) Distance between parallel lines__________ (7) a line passing through the midpoint of one side of a triangle and parallel to the other side must be bisected__________ .
3、 Parallel line segments are proportional
1. The theorem of parallel lines dividing into equal segments: if the segments of a group of parallel lines cut on one line are equal, then the segments cut on other lines are equal____ .
2. The corollaries of the theorem of parallel line bisection are as follows: (1) the middle point and the bottom of a trapezoid_____ (2) a line passing through the midpoint of one side of a triangle and parallel to the other side must be bisected__________ .
3. The theorem of parallel line segment proportion: three parallel lines cut two straight lines, and the corresponding line segment is proportional_________ .
4. Corollaries of the proportional theorem of parallel line segments__ 5. Theorem: if a line cuts the corresponding line proportion of two sides of a triangle, then the line is proportional_ On the third side of the triangle
Chapter 5 data collection and expression
&#In addition, we must master the knowledge of frequency and so on
The purpose of the data should be clarified;
The scope of data collection is determined;
Choose the survey method -- the method used to collect data;
Investigation data collection;
Record results -- data arrangement;
The conclusion is data analysis;
 Summary: frequency represents the number of times each object appears;
Frequency represents the ratio (or percentage) of the number of occurrences of each object to the total number of occurrences
Frequency and frequency can reflect the frequency of each object
 learn to use statistics to express data intuitively, and find the connection between data from statistical chart. Learn to draw statistical chart with computer
Chapter 6 one variable linear equation
1. Be able to properly deform the equation and solve the equation of one degree with one variable: the basic idea of solving the equation is transformation, that is, to deform the equation, two points should be paid attention to when deforming. For one thing, both sides of the equation can't be multiplied (or divided) by integers containing unknowns, otherwise the solution of the equation may be different from that of the original equation; for another thing, when removing the denominator, don't omit the term without denominator, Linear equation of one variable is the basic content of learning linear equations of two variables, quadratic equations of one variable, inequalities of one variable and function problems
2. Correctly understand the definition of equation solution and skillfully solve examination questions by applying the properties of equation: the solution of equation should be understood as that it is suitable to substitute it into the original equation, and the method is to substitute the solution of equation into the original equation, so that the problem can be transformed
3. Understand all kinds of solutions of the equation AX = B under different conditions, and be able to make simple applications: (1) when a ≠ 0, the equation has a unique solution x =;
(2) When a = 0, B = 0, the equation has innumerable solutions; (3) when a = 0, B ≠ 0, the equation has no solution
4. To solve application problems correctly, the key to solve application problems is to find the equivalent relationship in the problems. We can use chart, list and other methods. According to the analysis of examination questions in recent years, we should pay more attention to social hot spots, closely connect with practice, collect and process more information, and check whether the results are in line with the actual significance when solving application problems
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