Math CentralQuandaries & Queries


Question from Sara, a student:

I've been having a problem with this question. I'm in 7th grade algebra and no one in my family seems to remember the equation of a line...

The question is:

Write the equation of a line that is parallel to y=3x-2 through the point (-5,9).
I think the correct equation for this is y=3x+24.
But I have to write it in standard form, and I can't seem to figure out how to do that. Please answer soon! Thanks!

We have three responses for you

Hi Sara,

What you have done is correct, the equation of the line is y = 3x + 24.

The standard form of a line is y = mx + b. In this form m is the slope of the line and b is the y-intercept, that is the point (b, 0) is on the line. That is exactly the form you have, y = 3x + 24. The slope is 3 and (0, 24) is on the line.



Hi Sara.

Some people get confused between "standard form" and "general form".

General form looks like this:

Ax + By = C

where A, B and C are all integers and A is not negative.

To change your equation

y = 3x + 24

to general form:

3x - y = -24

Stephen La Rocque.



We are not sure we are using the terms correctly? Wikipedia says that

Ax + By = C is "standard form"

Ax + By + C = 0 is "general form" and

y = mx + b is just "slope-intercept" form.

Stephen La Rocque.

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