The line through (4,0) that is perpendicular to the line x+y=3
I am sort of lost and unsure if I am on the right track.

y-0=-1(x-4)
y-0=-1x+4
+0 +0

y=-1x + 4

Is this the answer in slope intercept form:confused:

Looks good, except watch the slope. The perp line has a slope which is the negative reciprocal of the slope of the given line. The given line has slope -1, so the slope of your line is 1, not -1.

Yes, you are in slope intercept form, y=mx+b. m is the slope and b is where it crosses the y axis.

As an aside, do not write the 1 in front of the x. Makes it look rather hackneyed, though, technically it's correct.

Does that help?

Quote:

---

Originally Posted by galactus

Looks good, except watch the slope. The perp line has a slope which is the negative reciprocal of the slope of the given line. The given line has slope -1, so the slope of your line is 1, not -1.

Yes, you are in slope intercept form, y=mx+b. m is the slope and b is where it crosses the y axis.

As an aside, do not write the 1 in front of the x. Makes it look rather hackneyed, though, technically it's correct.

Does that help?.

---

So, if I am understanding you correctly, you are saying that I do not need to put the 1 in front of the x since x by itself is an understood 1 correct? Second, the perpendicular line has a negative reciprocal of the slope given and since the answer ended with the slope being a -1 the reciprocal of that would be 1. The correct answer being... y= x - 4 ?

That should be y=x+4.

We know the slope is 1, so we can use y=mx+b to find b and finish.

4=1(0)+b, b=4

Therefore, the equation is y=x+4

Quote:

---

Originally Posted by galactus

That should be y=x+4.

We know the slope is 1, so we can use y=mx+b to find b and finish.

4=1(0)+b, b=4

Therefore, the equation is y=x+4

---

I am not understanding why it is a positive 4

Wrong substitution of y and x. The co ordinates that it passes through are 4,0 i.e.. x=4 y=0
Thus y= 1x + c ---> 0= 4 + c ----> c = -4

Yes, chris fixed it. I had the coordinates backwards. It is indeed y=x-4.

Sorry 'bout that.:o