"Solution of linear equations in two variables" PPT courseware 3

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"Solution of linear equations in two variables" PPT courseware 3

1. Fill in the blanks according to the properties of the equation:

<1>If a=b, then a±c=b±c. (Equation Property 1)

Thinking: If a=b,c=d, then a+c=b+d?

<2>If a=b, then ac=bc. (Equation Property 2)

2. What is the key to solving equations using the substitution method?

3. What is the basic idea of ​​solving a system of linear equations in two variables?

1. What is the basic idea of ​​solving a system of linear equations in two variables?

Basic idea: Elimination: two elements - one element

2. What are the steps to solve equations using the substitution method?

The main steps:

1. Deformation: Use an algebraic expression containing one unknown number to express another unknown number, written as y=ax+b or x=ay+b

2. Substitute Substitute the deformed equation into another equation and eliminate one element

3. Solve and find the values ​​of the two unknowns respectively.

4. Write the solution. Write the solution of the system of equations.

Summary: When the coefficients of the same unknown in two linear equations of two variables are opposite or equal, adding or subtracting both sides of the two equations can eliminate the unknown and obtain a linear equation of one variable. This method is called the addition, subtraction, and elimination method, or the addition and subtraction method for short.

Addition and subtraction induction:

When using addition and subtraction to solve a system of linear equations of two variables whose absolute values ​​of the coefficients of the same unknown are not equal and are not integer multiples, multiply both sides of one (or two) equations by appropriate numbers so that one of the two equations The absolute values ​​of the coefficients of the unknowns are equal, thus turning it into a system of equations of the first type to be solved.

Can you summarize what we have today?

1. In this lesson, we know that the basic idea of ​​using the addition, subtraction and elimination method to solve a system of linear equations in two variables is still "elimination". The main step is to eliminate one of the unknown numbers by adding (subtracting) the two equations.

2. Substitute the obtained solution into the original system of equations to check whether the problem-solving process is correct.

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For more information about the PPT courseware "Solutions to Systems of Linear Equations in Two Variables", please click on the "Solutions to Systems of Linear Equations in Two Variables" ppt tag.

"Solution of linear equations of two variables" PPT download:

"Solution of linear equations of two variables" PPT download Part 1: Review the past and learn the new What is the idea of ​​solving the system of linear equations of two variables? What is substitution elimination method? What are the steps for solving problems by substitution elimination method? Observe the following linear equations of two variables and look for their characteristics..

"Solution of linear equations of two variables" PPT:

"Solution to System of Quadratic Equations" PPT Part 1 Content: Give it a try The sum of the two numbers A and B is 9, and the number B is twice the number A. What are the numbers of A and B? Solution 1: Solution: Suppose the number A is x, then the number B is 2x. x+2x=9 Solution: x=3 23=6 Answer...

"Solution of linear equations of two variables" PPT courseware 2:

"Solutions to Systems of Linear Equations of Two Variables" PPT Courseware 2 Knowledge Review Question 1: What is a linear equation of two variables? An equation containing two unknowns whose terms are all of degree 1 is called a linear equation of two variables. Question 2: What is a system of linear equations in two variables? ..

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Update Time: 2024-10-18

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