Find the slope-intercept form of the given line that passes through the points (-4, -1) and (3, -3)???? Show full work.

Question

anonymous · Answer

Slope intercept form is the form $$y=mx+b$$ where m is the slope and y is the y-intercept

anonymous · Answer

do you know how to find the slope between the 2 given points?

anonymous · Answer

No, unfortunately I don't.

anonymous · Answer

That's alright! So here's the formula... $$m=\frac{ y _{2}-y _{1} }{ x _{2}-x _{1} }$$

anonymous · Answer

So how would you plug in those points into this formula?

anonymous · Answer

-3-(-1)/3-(-4)??

anonymous · Answer

Exactly! :D

anonymous · Answer

That simplifies to -1/7

anonymous · Answer

So that's our m, now we gotta find the b

anonymous · Answer

And this is what we have so far... $$y=-\frac{ 1 }{ 7 }x+b$$

anonymous · Answer

Okay, so how do you find b?

anonymous · Answer

Hold on a sec, lemme check if I'm doing this right

anonymous · Answer

Ah! Okay - so all you gotta do now is just choose any one of the 2 points and plug the x and y values as well as the slope... so that the only variable left in our equation is b. 
Forget what I said about x=0, i was confusing it with something else

anonymous · Answer

It doesn't matter which point??

anonymous · Answer

Nope, both should give you the same answer

sloppycanada · Answer

Nope. But I recommend doing the easier one to solve. Usually it's positive.

anonymous · Answer

So, wait...-4=-1/7(-1)+b????

anonymous · Answer

Yeah! You can do that! :)

anonymous · Answer

But what is b??

sloppycanada · Answer

You solve for b. Like you're solving a regular equation.

anonymous · Answer

^^ Exactly

sloppycanada · Answer

So if I were you I'd factor out one seventh of -1.

anonymous · Answer

what?...is b a whole or mixed number...cause i got like -29/7 which seems weird. I'm not good at math so bear with me.

anonymous · Answer

$$-4=-\frac{ 1 }{ 7 }(-1) + b$$
you can start by multiplying -1/7 and -1, you get $$-4=\frac{ 1 }{ 7 } +b$$ then you take 1/7 to the other side and you get $$-4-\frac{ 1 }{ 7 }=b$$
Can you take it on from here?

anonymous · Answer

i think so...

anonymous · Answer

you simply both sides and then isolate the b right?

anonymous · Answer

So it's $$b=-\frac{ 28 }{ 7 }-\frac{ 1 }{ 7 }=-\frac{ 29 }{ 7 }$$
That make sense? I used common denominators.

anonymous · Answer

yeah that's what I got, -29/7. So I just leave it like that?

anonymous · Answer

I always prefer fractions instead of decimals, but it's up to you.

anonymous · Answer

Awesome, thanks so much for your help! :)

anonymous · Answer

Your welcome :)