Systems of equations

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3)
3)
section 2: Chapter 3 Systems of Equations: Substitution
2)
2)
1)
1)
3x-6x-6=21
3x-6x-6=21
3x-3(2x+2)=21
3x-3(2x+2)=21
Y=2x+2 3x-3y=21
Y=2x+2 3x-3y=21
3x-3(2x+2)=21
3x-3(2x+2)=21
4)
3x-6x-6y=21
-3x-6y=21
Hi, I'm Zac and I am having trouble understanding this lesson. Can you help?
section 2: Chapter 3 Systems of Equations: Substitution
First, we substitute the x or y into the other equation.
2)
1)
3x-3(2x+2)=21
Y=2x+2 3x-3y=21
section 2: Chapter 3 Systems of Equations: Substitution
To find y, you must plug the value of the variable into one of the equations
6) y=2(-9)+2 y=-18+2 y=-16
section 2: Chapter 3 Systems of Equations: Substitution
Oh sure. I'm a mathematician. What is it that you need help with?
Oh, sure. I'm a good mathematician. What is it that you need help with?
I don't understand how to find X and Y when we use Substitution.
section 2: Chapter 3 Systems of Equations: Substitution
We can then distribute the 3 into the parenthesis.
I get it now since we don't need the parenthesis in the equation, it makes things more complicated.
section 2: Chapter 3 Systems of Equations: Substitution
Finally, you write your answer as a coordinate pair.
6) y=2(-9)+2 y=-18+2 y=-16
7) (x,y) (-9,-16)
section 2: Chapter 3 Systems of Equations: Substitution
Alright! Let me show you an example.
okay cool, thank you!
section 2: Chapter 3 Systems of Equations: Substitution
Next, combine like-terms in the equation.
section 2: Chapter 3 Systems of Equations: Substitution
So, we start off with the equations Y=2x+2 & 3x-3y=21. (Make sure at least one of the equations is in slope-intersect form.)
1)
Y=2x+2 3x-3y=21
section 2: Chapter 3 Systems of Equations: Substitution
3)
Now, with the remaining numbers divide both sides by the coefficient and you are left with the value of x.
2)
1)
3x-6x-6=21
3x-3(2x+2)=21
Y=2x+2 3x-3y=21
3x-3(2x+2)=21
4)
3x-6x-6=21
5) -3x=27 x=-9
-3x-6=21