Sunday, May 2, 2010

Posting...#37

Normal lines:

Normal lines have the same steps and tangent lines but when you find the slope you have to take the reciprocal.

Example:

An equation of the line normal to the graph of y = (3x^2 +2x)^1/2 at (2,4) is

1. Since you already have a point, you do not need to plug in the x to find the y.

2. Derivative: 1/2 (3x^2 + 2x) ^ -1/2 (6x +2)
Plug in x to find slope: 6(2) +2 / 2 (3(2)^2 + 2(2)) ^1/2
14/8 = 7/4
Since this is normal, we need the negative reciprocal of the slope, which is -4/7

3. Now we can plug in: y-4 = -4/7 (x-2)

Than change what you got and find your awnser choice

7y - 28 = -4 (x-2)
7y - 28 = -4x + 8
7y = -4x + 36
4x + 7y = 36

What i'm having trouble with is:

Someone help me find AREA,

and... Trapazoidal

3 comments:

  1. To find area, you can use any of the reimann sums, and to find area on a graph, you find the area of all the shapes and add them together

    ReplyDelete
  2. here ya goooo.....

    Trapezoidal- x/2[f(a)+2f(a+x)+2f(a+2x)+...f(b)]

    ReplyDelete
  3. Trapezoidal is the easiest formula to remember once you've got it down because none of the others are like it and it's just plugging in after you've got it

    delta(x)=b-a/n
    TRAM: delta(x)/2[f(a)}2f(a+delta(x))+2f(a+2delta(x))+2f(a+3delta(x))....+f(b)]

    ReplyDelete