Results 1 to 8 of 8

Math Help - How to find the slopes of:

  1. #1
    Junior Member
    Joined
    Jul 2009
    Posts
    47

    How to find the slopes of:

    y = (3x + 1)^2

    and

    y = (2x - 5) / (3x + 2)^2
    Follow Math Help Forum on Facebook and Google+

  2. #2
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    Quote Originally Posted by marie7 View Post
    y = (3x + 1)^2

    and

    y = (2x - 5) / (3x + 2)^2
    Not enough info marie. Do you have any relevant points. Or you are trying to find a derivative, or what...

    Let me know, and I'll jump on it.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Jul 2009
    Posts
    47
    omg oops I forgot!!!! It says find slopes of the functions at x = 1
    My bad!
    Follow Math Help Forum on Facebook and Google+

  4. #4
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    Quote Originally Posted by marie7 View Post
    omg oops I forgot!!!! It says find slopes of the functions at x = 1
    My bad!
    OK. No problem. The slope at any value on a graph is given by the derivative of the function evaluated at that point. So, first we need the derivative. Do you know how to use the chain rule?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Jul 2009
    Posts
    47
    I already got an answer y = 18x + 6

    ohhhh and then there's the formula y = mx + c

    am I onto something here?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    Quote Originally Posted by marie7 View Post
    I already got an answer y' = 18x + 6
    OK. Good. You've found the derivative y'=18x+6. (Don't forget the apostophe, marie. It let's peolpe know that this is the derivative.)
    Now, all ya gotta do to find the slope is to plug in 1. IE y'=18(1)+6. This gives you the slope.

    As far as, y=mx+b is concerned, we don't need it here because all we want is m. The rest of the equation doesn't concern us. Got it?
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    Jul 2009
    Posts
    47
    Cool, gotcha. How about b)?
    Follow Math Help Forum on Facebook and Google+

  8. #8
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    For b) we need the quotient and chain rules.

     <br />
\frac{d}{dx}\left[\frac{2x-5}{(3x+2)^2}\right]=\frac{(3x+2)^2\cdot(2)-(2x-5)\cdot(2)(3x+2)(3)}{[(3x+2)^2]^2}<br />

    After you simplify, plug in 1.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. slopes
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: October 2nd 2008, 09:36 AM
  2. help with slopes!
    Posted in the Pre-Calculus Forum
    Replies: 7
    Last Post: May 3rd 2007, 02:59 PM
  3. slopes
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 22nd 2007, 08:54 AM
  4. need help on Slopes
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: November 18th 2006, 10:05 AM
  5. Slopes Help
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: November 14th 2006, 04:27 AM

Search Tags


/mathhelpforum @mathhelpforum