Fina an equation of the line that has the given slope and passes through the given point.
m=-3 (1/2,2)

Question

Fina an equation of the line that has the given slope and passes through the given point.
m=-3 (1/2,2)

polaris_s0i · Answer

$$ y = -3x + b $$
$$ 2 = -3x + \frac{1}{2} $$

now solve.

vshiroky · Answer

I got y=-3x+5/2

polaris_s0i · Answer

er sorry
$$ 2 = -3(\frac{1}{2}) + b $$

vshiroky · Answer

is mine correct?

polaris_s0i · Answer

you tell me... plugin (1/2) into x

vshiroky · Answer

Isn't it y-y1=-3(x-x1)

vshiroky · Answer

I did the problem I just don't know if I am correct

polaris_s0i · Answer

no, you're confused... we aren't finding the distance of anything, no y1 y2 stuff here.
just set x to 1/2 and solve for y, if you get 2 then you are correct.

vshiroky · Answer

Yeah I dont get it

polaris_s0i · Answer

lol, maybe I'll explain then.

vshiroky · Answer

It's supposed to be in slope intercept form

vshiroky · Answer

Is it y=-3x+9/2

polaris_s0i · Answer

line has slope -3.
we know a line has an equation of the form y = mx +b
where m is the slope.

so y = -3x + b is what we know.
We also know the point it's going through, so that is a specific x and y coordinate.
we can set the equation to:

$$ 2 = -3(\frac{1}{2}) + b$$
and solve for b, because we absolutely want the line to go through this point.

$$ 2 = -\frac{3}{2} + b $$
$$ \frac{4}{2} + \frac{3}{2} = b $$
$$ \frac{7}{2} = b $$

so now we have the equation
$$ y = -3x + \frac{7}{2} $$

if we plug our original x coordinate in, we had better get 2, since that is what we designed it to do:

$$ y = -3\frac{1}{2} + \frac{7}{2} $$
$$ y = -\frac{3}{2} + \frac{7}{2} $$
$$ y = \frac{4}{2}  $$
$$ y = 2  $$

vshiroky · Answer

This isn't slope intercept form though

polaris_s0i · Answer

"slope-intercept" form:

y = mx + b

vshiroky · Answer

Right so wouldn't it be y=-3x+9/2

vshiroky · Answer

You just have y=2

polaris_s0i · Answer

where is the 9/2 coming from?
I have: 
$$ y=−3x+\frac{7}{2} $$

polaris_s0i · Answer

y =2 was me checking to make sure its write.

vshiroky · Answer

When I added the 2 from the other side

polaris_s0i · Answer

can you show me you're calculations?

vshiroky · Answer

I am running out of time

vshiroky · Answer

I did y-2=-3(x-1/2)
y-2=-3x+7/2
y=-3x+9/2

polaris_s0i · Answer

no, that is incorrect.
you're not doing the correct thing.

you need to READ THE WHOLE ANSWER I gave above, because you are not understanding the WHY of what you are doing, you're following method without reason.

vshiroky · Answer

Ok