Question

Part 1: Decide whether you would use the graphing, substitution, or elimination method to solve the following system of equations. Explain, in complete sentences, why you chose that method.
Part 2: Solve the following system of equations and show all of your work.

4x + 3y = -1
3x + y = 3

Answer 1

ok the last time, I used the elimination method because we would have ended up with fractions when we tried to solve for any variable, can you solve for a variable in either one of these equations?
hint: the second one....solve for y. then tell me what you got.

Answer 2

Use elimination.

Answer 3

shouldn't it be a fraction?

Answer 4

y=3-3x

Answer 5

wait I got two

Answer 6

y=3-3x

Answer 7

using subsitution.

Answer 8

so its pretty easy to now pluf in y=3-3x into the first equation and then solve for x.

Answer 9

pluf=plug

Answer 10

if you have a fraction, it will be the last step and it will not have variables...

Answer 11

you want to use substitution, in algegebra they taught us that if any time you have a variable by its self, in this case the y use substitution.

Answer 12

good idea^^

Answer 13

true. :)

Answer 14

no fractions:)

Answer 15

i ment algebra

Answer 16

I think elimination is much faster, and with a little practice, you can do it in your head pretty fast, but....to each their own. Just know why you are picking one over the other.

Answer 17

so y equals 13x plus 3

Answer 18

so 4x+3(3-3x)=-1
4x+9-9=-1
4x=-1
x=-4

Answer 19

substitution might not be the fastest way, but i just took algebra last year and they said if thers a variable by its self use substition, i would put that since thats what they "want"

Answer 20

Sometimes Substitution is pretty fast....annoying summer hw. :(

Answer 21

4x+3(13x+3)

Answer 22

I would personally use whatever way you are most comfortable with, or whichever way has the least possibility of error. Just my 2 cents worth.

Answer 23

im confused

Answer 24

distribute to find x, then plug it

Answer 25

4x + 3y = -1
3x + y = 3

one method
y=3-3x
plug into first equation
4x+3(3-3x)=-1
4x+9-9x=-1
-5x=-10
x=2
pluf this into either to solve for y
y=3-3*2
y=-3
so(2,-3)

second method
4x + 3y = -1
3x + y = 3

multiply second equation by -3
4x + 3y = -1
-9x - 3y = -9
add them
-5x=-10
x=2
plug in solve for y
y=-3

third method
graph them, this is lame and takes time.....these are linear so to easy to solve.

Answer 26

do u understand now?

Answer 27

@jaderbrown

Answer 28

@jaderbrown

Answer 29

first method = substitution
second method = elimination
I think second is way easy, but you do it both ways and decide.

Answer 30

yes thank you!

Answer 31

most people would use substitution here...

Answer 32

I think:)

Answer 33

Substitution is probably the easiest and most straight forward method for this particular problem. It is glaringly obvious by the lone y variable in the second equation.

Answer 34

and actually I misspoke, these are not linear equations. They are called affine. Linear must go through the origin.