Question

Solve the system using substitution.

x + y = 8

y = 3x

Answer 1

look for x+y=8 for y we put 3x and it means that x +3x=8
4x=8 x=2

Answer 2

why?

Answer 3

we know that y= 3x in another equation we only put not y but this 3x, that all that you need to do

Answer 4

But x + 3x = 8 isn't an answer choice.

Answer 5

Okay, isolate a variable to one side of the equation. For instance:\[x + y = 8 \]Isolate:\[y=8-x\]
Substitute y into the other equation! :)
\[8 - x =3x\]Add x.
\[8=4x\]Divide.\[2 = x\]

Answer 6

Is that easier to understand?

Answer 7

I dont understand.

Answer 8

Substitute 3x for y
x + 3x = 8

Add the x's
4x = 8

Divide by 4 to get the x by itself
x = 2

Plug 2 into the bottom equation for x

y = 3(2)

Multiply
y = 6

Your answers:
x = 2
y = 6

Answer 9

you understood?

Answer 10

Look at the two equations you have.

x + y = 8
y = 3x

In the first equation x + y = 8, I moved x by subtracting it by both sides.

So..
y = 8 - x <--- REPLACE Y IN THE OTHER EQUATION WITH THIS.

Now SUBSTITUTE Y. LOOK AT YOUR SECOND EQUATION NOW.
y = 3x
^
|

8 - x = 3x

Add x.

8 = 4x

Divide 4 by both sides.

2 = x

Answer 11

@trenten 3 + 1

Answer 12

lol yeah I understand now. Thanks

Answer 13

^ ^ .

Answer 14

what? how was that hurtful? I said yours was the Best Response.. uh okay?

Answer 15

how am I wrong?

Answer 16

Being sarcastic, do enjoy your evening.

Answer 17

weird. okay.

Answer 18

If there's no other clarifying question, don't forget to close out. Though, it's at your discretion.