Question

Part 1: Explain, in complete sentences, how you would use the substitution method to solve the following system of equations. (4 points)

Part 2: Provide the solution to the system. (2 points)

x + 6y = 1
2x + 5y = 9

Answer 1

Hey, do you have any idea how you would begin to solve this?

Answer 2

dude i have no clue whatsoever how to do this..

Answer 3

In that case. Let's solve a completely related problem!

Answer 4

5x + y = 1
-3x + 9y = 9
Okay...
So we are supposed to use substitution right?

Answer 5

yes

Answer 6

btw, I'm not doing ur problem, cause I"m afraid I"m cheating on a test for you. THat would be bad, wouldn't it ;)

Answer 7

but ur not! my friend has this very complicated worksheet and he has been stuck on this problem for hours! so i wanted to surprise him with the answer..

Answer 8

5x + y = 1
-3x + 9y = 9
Now, we want to find an equation where we move a variable to one side, and "substitute" it in.

Answer 9

I don't want to help your "friend" cheat on his worksheet :)

Answer 10

ok..welll at least help me please?

Answer 11

Sure. That's what I'm doing this example question for. I can do as many of these as I want and I won't be cheating or helping people cheat :)

Answer 12

ok well continue please?

Answer 13

5x + y = 1 ->call this eq1
-3x + 9y = 9 ->call this eq2

Answer 14

eq1:
5x+y=1
-> y=1-5x

Answer 15

eq2:
-3x+9y=9
-3x+9(y)=9

Answer 16

But, we know from eq1 that (y)=1-5x

Answer 17

so, -3x+9(1-5x)=9
This is the biggest part. Tell me if it makes sense or not.

Answer 18

it does

Answer 19

I got rid of the y. Now there are just x's. Why don't we solve that now.

Answer 20

-3x+9(1-5x)=9
-3x+9-45x=9
-48x=0
x=0

Answer 21

BUT WHAT DOES Y EQUAL?

Answer 22

5(x) + y = 1 -> eq1
-3(x) + 9y = 9 -> eq2
we know x equals 0...

Answer 23

Working with either equation at this point to find y works. I'll just do eq1
5(x)+y=1
but x=0
5(0)+y=1
0+y=1
y=1

Answer 24

In other words, x=0, y=1

Answer 25

hmmmm ok, ok let me look over this..

Answer 26

Look over it long and hard, and when you are ready, let's do the actual test problem :)

Answer 27

Actually, you'll be doing most of the work, while I nudge you along. I don't like getting banned by moderators for helping people cheat :P

Answer 28

im so sorry i fell asleep. but ended up figuring it out thank you!