"Solution of linear equations of two variables" PPT download

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"Solution of linear equations of two variables" PPT download

Part One: Review the past and learn the new

What is the idea of ​​solving a system of linear equations in 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.

5x+3y=16 ①

2x-3y=-2 ②

The coefficients of y in the two equations are opposite to each other.

Problem-solving ideas: According to the first property of the equation, ①② the addition equation still holds. Can be eliminated.

That is: 5x+2x+3y-3y=16-2

Summary

When the coefficients of the same unknown number in two equations are opposite or equal to each other, it is simpler to "eliminate" by adding (or subtracting) the left and right sides of the two equations.

Solution to system of linear equations in two variables PPT, Part 2: Solving system of equations

3X-4Y=10 ①

5X+6Y=42 ②

Analysis: We must try to make the absolute values ​​of the coefficients of the same unknown equal.

Think about it: What if direct addition and subtraction cannot eliminate an unknown number?

(1) If Y is eliminated, the absolute values ​​of the unknown Y coefficients of the two equations are 4 and 6 respectively. Just make them 12 (the least common multiple of 4, 6), just

①×3, ②×2:

9X-12Y=30 10X+12Y=84

(2) If X is eliminated, as long as the unknown X coefficient of the two equations becomes 15 (the least common multiple of 3, 5), as long as

①×5, ②×3:

15X-20Y=50 15X+18Y=126

Solution to linear equations in two variables PPT, part 3: Solve the following equations:

(1). 3X-2Y=6

2X+3Y=17

(2). 4X-2Y=14

5X+Y=7

(3). 2X-3Y=8

5Y-7X=5

(4). X-3Y=-20

3X+7Y=100

Keywords: Free download of Hebei Education Edition mathematics PPT courseware for the second volume of seventh grade, PPT download of solutions to linear equations in two variables, .PPT format;

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.

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Update Time: 2024-10-14

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