Question

what is the intersection of the equation y=3x-4 over y= -3x -4

Answer 1

you would set these 2 equations equal to each other :)

Answer 2

Start with one equation and plug in the other

y=3x-4 ... start with the first equation

-3x - 4 = 3x - 4 ... plug in y = -3x - 4 (the second equation)

Answer 3

So you now need to solve

-3x - 4 = 3x - 4

for x

Answer 4

you see how y equals..2 different equations? well....logic will say that those 2 equations are also equal correct? that is why you can set them equal to each other

so

3x-4 = -3x -4

now solve for x

Answer 5

so would i add 3 to -3x?

Answer 6

you would combine the like terms....add 3x to both sides

Answer 7

so

3x - 4 = -3x - 4
+3x +3x

now we have

6x - 4 = -4

now we 6x by itself so we...?

Answer 8

subtract 6x from -4? making -2??

Answer 9

or do i add 4 to -4?

Answer 10

you add 4 to both sides yes

(you cannot combine an "x" number and a normal number!)

so

6x - 4 = -4
+4 +4

6x = 0

what is 0?

Answer 11

woops lol...what is x :P

Answer 12

x is just 6 right? since nothing can be divided by 0?

Answer 13

you want x to be completely by itself so you would actually divide both sides by 6

6x = 0
-- --
6 6

x = 0

Answer 14

so that says the lines will intersect when x = 0...does it make sense? want to know something funny?

Answer 15

sure! and thank you, yes (: that makes plenty sense!

Answer 16

haha and just in case you need an extra view of it...

your 2 lines are

y=3x-4 and y= -3x -4

they both have the same y-intercept....

if they both cross through y at -4...then that means that at x = 0 they cross....indeed because that is what we just solved for :)

Answer 17

awesome (: thanks again.

Answer 18

anytime :)