Week 16- Math 10- Solving by Elimination

To solve a system using elimination you need to see which number you will need to cancel out.

ex.

3x + 2y = 9

2x + 6y = 6

in order to eliminate either the x or y value you will have to make a zero pair. in order to make a zero pair you must multiple each equation by a certain number to cross one out.

for this equation I am going to multiply the 3x and 2x so that I can cancel it out to find the y value first. In order to make it a zero pair i need to find a number they can both multiply to thats small. But in order to make a zero pair one must be positive and the other must be negative to equal to 0.

for 2 ill multiply that system by -3 and for 3 ill multiply the system by 2 so the gcf can be 6.

2(3x + 2y = 9)

-3(2x + 6y = 6)

this would change the systems to…

6x + 4y = 18

-6x – 18y = -18

then you need to remove the zero pair (-6x, 6x)

so the equation would now look like:

4y = 18

-18y = -18

then you add each number

so it would now look like

-14y = 0

s0 y would =0

(x, 0)

then to find the x you plug in one of the y values with 0 to either system

3x  + 2(0) = 9

3x =9

divide by 3 to put x by itself to = 3

so the answer would be

(3, 0)

 

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