Expert: Paul Klarreich - 5/4/2008

Question
Dear Paul,

Is the slope of this line:

3x - 5y = -15

- 3/15 ?

Thanks,

Julie  

Answer
Questioner:   Julie
Category:  Advanced Math
Private:  No
 
Subject:  algebra
Question:  Dear Paul,

Is the slope of this line:

3x - 5y = -15

- 3/15 ?

Thanks,

Julie
..............................
Hi, Julie,

Welcome to the site.  As to your question:

Is the slope of this line:
3x - 5y = -15
- 3/15 ?

No, it is not.  You want to look at the 'slope-intercept' form of the equation of a line:

y = mx + b,

then match things up.  So you must solve:

3x - 5y = -15

- 5y = -15 - 3x

Divide:

y = -15/(-5) - 3x/(-5)

y = +3x/5 + 3

Now the coefficient of x is 3/5 and that matches up with 'm', so your slope is 3/5.

In the 'general form' of a line, [Believe me, there are more forms for a straight line equation than you care to know.] which is:

Ax + By = C.  [big A,B,C, please.]

The slope would be  -A/B.

In your case:

3x - 5y = -15,  A = 3,  B = -5, slope is -3/(-5) = 3/5.

That should do it.