"Method of Addition, Subtraction and Elimination—Solution to Systems of Linear Equations in Two Variables" System of Linear Equations in Two Variables PPT Courseware 3

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"Method of Addition, Subtraction and Elimination—Solution to Systems of Linear Equations in Two Variables" System 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=_____.(Equation Property 1)

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

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

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

Binary elimination transformation---one dollar

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

Elimination: two elements---one element

1: 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.

1. Fill in the blanks:

1. Known equations x+3y=17 2x-3y=6 two equations

As long as both sides are added separately, the unknown y can be eliminated.

2. Known equations 25x-7y=16 25x+6y=10 two equations

As long as both sides are subtracted, the unknown x can be eliminated

2: Use addition and subtraction to solve systems of linear equations in two variables.

⑴7x-2y=3 x=-1

9x+2y=-19 y=-5

⑵6x-5y=3 x=-2

6x+y=-15 y=-3

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 "Method of Addition, Subtraction and Elimination of Elements for Systems of Linear Equations in Two Variables", please click on the tag Addition, Subtraction and Elimination of Elements for Systems of Linear Equations in Two Elements ppt.

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Update Time: 2024-10-20

This template belongs to Mathematics courseware People's Education Press Seventh Grade Mathematics Volume 2 industry PPT template

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