Need some help with X and Y Intercepts...

[Sembhi]

Hello everyone, I just registered and I had a few question about some math stuff I'm having a hard time understanding.

My teacher gave this assignment to me and I can't seem to figure a couple out:

Write and equation in slope-intercept form for the line that contains the points (1,2).

- Parallel to 3x - 6y=12
- Perpendicular to 3x -6y = 13

Write in standard form.

- Contians the points (2,-3) and has a slope of 5.

and the last problem...

Crosses the x-axis at x=-3 and the y-axis at y=1.

- Write an equation for the line that contains each pair of points.
- (4,3) (-2,-9)
- (-7,2) (5,-1)

Alright, thats all. I would love it if someone could tell me how to do these.

 

[stapel]

There are various methods for finding the equation of a line with a given slope m and given y-intercept b. Which method or formula are you using?

For the parallel and perpendicular stuff, keep in mind that parallel lines have the same slope, and perpendicular lines have slopes which are "negative reciprocals" (that is, opposite signs and flipped, like 1/3 and -3, or 2/5 and -5/2).

You will need to tell us what your book means by "standard form", because this term does not, unfortunately, have any standardized meaning (no pun intended).

For the last three exercises, in which they give you two points and want a line equation, the first step would be to find the slope, so plug the points into the slope formula you memorized.

Eliz.

 

[Sembhi]

There are various methods for finding the equation of a line with a given slope m and given y-intercept b. Which method or formula are you using?

y=mx+b. My teacher taught me to use that forumla for Slope-Intercept problems. And to find the slope I was told to do

You will need to tell us what your book means by "standard form", because this term does not, unfortunately, have any standardized meaning (no pun intended).

Ax+By=C

Thanks for your help so far.

 

[galactus]

Hello everyone, I just registered and I had a few question about some math stuff I'm having a hard time understanding.

My teacher gave this assignment to me and I can't seem to figure a couple out:

Write and equation in slope-intercept form for the line that contains the points (1,2).

- Parallel to 3x - 6y=12
- Perpendicular to 3x -6y = 13

You have a line equation in standard form. Solve it for y; Since the lines are parallel, the slopes are the same(3). Use the slope-intercept form and enter in the values you were given(1,2), solve for b. You now have your equation.

For the perpendicular line, it's as Stapel said, use the negative reciprocal of the slope of the line given.

[quote:21fzm6gx]Write in standard form.

- Contians the points (2,-3) and has a slope of 5.

and the last problem...

Crosses the x-axis at x=-3 and the y-axis at y=1.

- Write an equation for the line that contains each pair of points.
- (4,3) (-2,-9)
- (-7,2) (5,-1)

Alright, thats all. I would love it if someone could tell me how to do these. [/quote:21fzm6gx]

 

[Sembhi]

You have a line equation in standard form. Solve it for y; Since the lines are parallel, the slopes are the same(3). Use the slope-intercept form and enter in the values you were given(1,2), solve for b. You now have your equation.

For the perpendicular line, it's as Stapel said, use the negative reciprocal of the slope of the line given.

How exactly do I do this?

Add 6 to both sides?

 

[stapel]

Which method or formula are you using?

My teacher taught me to use [y=mx+b] for Slope-Intercept problems.

So you'll be plugging x, y, and m into the formula and finding b, or else plugging m and b into the formula and you're done, depending on the info you've got. How far you have gotten in this process?

And to find the slope I was told to do \(\displaystyle m\,=\,\frac{y_1\,-\,y_2}{x_1\,-\,x_2}\)

That's the right formula. Now plug your numbers in, and simplify to find the slopes.

You will need to tell us what your book means by "standard form"...

Ax+By=C

Thank you. Now how far have you gotten in apply the formulas?

Please reply showing all of your steps.

Eliz.

 

[Sembhi]

Alright I'm going to do each problem step by step, I'll start of with this one.

Write an equation for the line that contains each pair of points.

(4,3) (-2,-9)

So first I have to find the slope, right?

I used this formula,

, to find the slope, I got -2 by doing (-9 - 3 OVER -2 - 4)

So far so good?

 

[Mrspi]

Alright I'm going to do each problem step by step, I'll start of with this one.

Write an equation for the line that contains each pair of points.

(4,3) (-2,-9)

So first I have to find the slope, right?

I used this formula,

, to find the slope, I got -2 by doing (-9 - 3 OVER -2 - 4)

So far so good?

You substituted correctly, but made an arithmetic mistake:
(-9 - 3) / (-2 - 4) is (-12) / (-6)

You should get a POSITIVE result.

Be very careful with the arithmetic, because a simple error like the one you made can doom your "final answer"

 

[Sembhi]

Ah, I knew it! Two negatives equal a positive.

Alright, on Friday my teacher said if no specific equation form is given just put it in point slope form, which is y-y1=m(x-x1)

I'm getting a little confused here.

y-(-2)=2(x-3)
Simplified: y+2=2(x-3)

Now, I'm not sure if I substiuted the y1 and x1 correctly. The original point pairs were (4,3) and (-2,-9). I figured m was 2 by doing

Did I do it correctly?

 

[Sembhi]

I'm having trouble with this one the most,

crosses the x-axix at x=-3 and the y-axis at y=1

What the heck am I supposed to do? :?:

 

[stapel]

I'm having trouble with this one the most:
crosses the x-axix at x=-3 and the y-axis at y=1
What the heck am I supposed to do?

Take the two points they've given you, plug them into the "slope" formula, and find slope "m". Then take the slope value you've found and the y-intercept value they gave you, then plug them into the slope-intercept form you've memorized.

Eliz.

 

[Sembhi]

How do I put them in the slope formula? Isn't the slope forumla y1-y2 over x1-x2? I only have two numbers that are alone, don't I need pairs?

 

[stapel]

I only have two numbers that are alone, don't I need pairs?

When you cross an axis, what is the value of the other variable?

Eliz.

 

[Sembhi]

0?

 

[stapel]

0?

You're not sure...?

Draw the plane with the axes, and try some points, until you are sure, because this exercise expects you to know this basic property.

Eliz.

 

[Sembhi]

Eh, I did the last two and the standard form problem. The rest I can't quite get, I'll just get help from a friend. Thanks for your help everyone.