Question

HELP PLEASE!!!!
If you were to use the substitution method to solve the following system, choose the new equation after the expression equivalent to x from the first equation is substituted into the second equation.

-x + 5y = 1
2x + 4y = -4

Answer 1

@terenzreignz

Answer 2

hey can you help me

Answer 3

Okay, substitution, the most basic method, possibly the easiest, but not always the most efficient :)
You have two equations
-x + 5y = 1
and
2x + 4y = -4

The way to do this is to solve for x in the first equation (or second, really, but first is easier).
What I mean is that rearrange the first equation so that x stands alone in one side of the equal sign.

Answer 4

a. 2(5y - 1) + 4y = -4
b. 2(-5y + 1) + 4y = -4
c. 2x + 4(-5y + 1) = -4
d. 2x + 4(5y - 1) = -4
these are the possible answers

Answer 5

Yeah... might be to your benefit to pretend we don't have choices for now.
Let's look at the first equation.
-x + 5y = 1
If we subtract 5y from both sides, what do we get?

Answer 6

1-5y=-x

Answer 7

That's right. But that's a -x
How do we get rid of that negative sign?

Answer 8

multiply both sides by neg1

Answer 9

and you get...?

Answer 10

2x=-1+5y

Answer 11

Why 2x?
How did you get 2x?
-x = 1 - 5y
multiply both sides by -1
-1(-x) = -1(1 - 5y)

Answer 12

ok so x=-1+5y

Answer 13

or x = 5y - 1
Now, given your SECOND equation
2x + 4y = -1
replace the x here with the right-hand side of your first equation modified:
x = 5y - 1

Answer 14

2(5y-1)+4y=-1

Answer 15

Sorry, it was
2x + 4y = -4

Answer 16

thats isn't even one of the answers

Answer 17

I know. I made a typo.
2x + 4y = -4
and replace the x with the expression in terms of y.
x = 5y - 1

Answer 18

so what is the answer

Answer 19

abc or d

Answer 20

so d

Answer 21

You replace the x in
2x + 4y = -4
with 5y - 1

Answer 22

so a

Answer 23

Yeap...

Answer 24

hey i just posted another ? can you come help me