5/19 Alg1: Introduction to Solving by Substitution

• Graph the system of equations

• Identify the point of intersection: this is the solution to the system!

I can solve a system of equations by substitution.

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x+y = 4 x = 3

Take a look at the graph of the system. What do you notice about the solution?

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y = -x + 4 y = 3

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The answer should be an (x, y) point that exists on both lines. 

We know y has to equal 3, and we found that x has to equal 1.  SOLUTION: (1, 3)

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 y = x + 2

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What can we do now?

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If they made the same number of 2-point shots as 3-point shots, how many 2-point shots did they make?

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How many 3-point shots did they make?

• A basketball team scored 45 points through a combination of both 2-pointers and 3-pointers.

• They made the same number of 2-point shots as they did 3-point shots.

• Equation 1:

• Equation 2:

• A basketball team scored 45 points through a combination of both 2-pointers and 3-pointers.

• They made the same number of 2-point shots as they did 3-point shots.

• Solve for x and y.

Learning Target: I can solve a system of equations by substitution.

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There are 3 methods of solving systems of equations: we know of graphing and substitution.

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To solve by substitution, solve one of the equations to be set equal to one variable (y or x) and substitute into the other equation. Solve for both variables.

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Great work today! COMPLETE YOUR EXIT TICKET.