Question

How to I make x - y =2 into y=mx+b format? I got y = x + 2 ,however, the correct answer is y = x - 2.

Answer 1

Best way to do this is to take it slowly, until you really get the hang of it. We want to put y on one side of the equation, right?
Start with
x - y = 2
What was the first thing you did?

Answer 2

Oh! Duh I see now.

First you subtract x from both sides to get "y = 2 - x" right?

Answer 3

Yeah, but there's a problem :P
The minus sign near y just disappeared... where did it go? XD

Answer 4

Ah I see, so -y = 2 - x?

Answer 5

I also have another question, I'm doing another problem and I have to graph y = 6 - x. How do I graph -x? -x is equal to -1 right?

Answer 6

That's right. So you *almost* have y alone on one side, just need to get rid of that annoying minus-sign. There are two ways to do it, one of them significantly quicker than ther other.

Answer 7

Okay, graphing lines is about the simplest graphs you could possibly do in your entire Maths career, so pay attention :)

Let's start with a cartesian plane

Answer 8

Just a warning, though. I suck at drawing, so just bear with me. The key to graphing lines is to find its intercepts. More than that, really just find two points.

You know what intercepts are?

Answer 9

yes, the point in which the line touches the x or y plane, for example the y-intercept 5 would be (0,5)

am i correct?

Answer 10

You're correct in your definition, but off with your example :)
Let's rewrite the linear equation
y = 6 - x

to get its y intercept, just fix x = 0, and what do you get?

Answer 11

Hmmm, if x = 0 then the y intercept is 0?

Answer 12

No... if x = 0, solve for y.

Answer 13

Uhh. if x = 0 then y = 6?? sorry I'm a bit tired x_x

Answer 14

Correct :)
When x = 0, y = 6
so, the point (0, 6) is in the line. Let's mark it out.

Answer 15

Now, to get the OTHER intercept. THIS time, set y = 0, then solve for x. Go ahead now :P

Answer 16

x + 0 = 6 > x = 6?

Answer 17

That's right :) So the point (6 , 0) is also on the line. Let's mark it out.

Can you see where we're going with this?