Question

Im very confused please explain this in simple terms please! (graph is attached) This is the graph of which equation?

2x + 6y = 12
6x - 4y = 0
4x - 6y = 24
5x + 4y = 24

Answer 1

this explains plotting a line
http://www.khanacademy.org/math/algebra/linear-equations-and-inequalitie/v/algebra--graphing-lines-1

Answer 2

i know how to do that buti need to do it the other way around from graph t equation. but thanks for the help.

Answer 3

one way to do this is pick an (x,y) pair that is on the line I would try (0,-4) because we see that pair is on the number, and using zero is easy.
try x=0 y=-4 in each equation and see which one is true

Answer 4

another way to do the problem is pick two pair of points example (0,-4) and (6,0)
and find the equation of the line through those points. Put the equation in standard form to match the choices. One of the choices should match your equation

Answer 5

how would i do that i mean put those in standard form?

Answer 6

i have tried but ended up with something like -2/-3x+-4 and thats not an option

Answer 7

first ,you should have an x and y
I would find the slope and y intercept. the slope is change in y divided by change in x
with
(0,-4) and (6,0)
-4-0 / 0-6 = -4/-6 = 2/3
y intercept is -4 (we can see it on the graph
in slope intercept form you get
y= (2/3)x-4
move the 2/3 x to the left side
multiply by -3 (all terms, both sides)
can you do that?

Answer 8

wait where did the -3 come from?i can do the equation but i dont see where that came from.

Answer 9

do this in steps:
start with
y= (2/3)x-4

move the (2/3)x to the left side

Answer 10

so y(3/2)=2/3(3/2)x-4
y(3/2)=x-4

Answer 11

or does the x go with the 3/2 like this y(3/2)x=-4

Answer 12

oops. you add a -2/3 x to both sides
\[ y= \frac{2}{3}x-4\]
\[ -\frac{2}{3}x+y= \frac{2}{3}x-\frac{2}{3}x-4\]
It is hard to see with fractions by the stuff on the right side cancels to leave just -4
\[ -\frac{2}{3}x+y= -4\]
now multiply both sides by -3.
\[ -3\cdot -\frac{2}{3}x+-3\cdot y= -3\cdot-4\]
\[ 2x-3y= 12\]

Answer 13

but thats not one of the options the closest one to that is 2x + 6y = 12

Answer 14

yes, this is tricky. notice that if you simplify one of the choices (divide all terms by 2) you will get this answer

Answer 15

so thats the answer?

Answer 16

we got
2x-3y=12

we could multiply both sides by 2
2(2x-3y)= 2*12 (it is still a true equation)
or, distributing the 2:
4x-6y= 24

Answer 17

oh ok so itsthe third answer! im not one of those people who just try to get the answer i want to knw how to do it.

Answer 18

yes.
If you are ambitious, try the other way to answer the question: try (0,-4) in each of the choices and see which one works.

Answer 19

4(0)-6(-4)=24
0--24=
0+24=
24=24 :)
thanks for taking the time to help me :)! you deserve a best answer :)

Answer 20

I got it right too!