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Christos
 one year ago
Limits,
Can you help me find out this specific thing I dont know how to find out
http://screencast.com/t/PUvesX4N
Christos
 one year ago
Limits, Can you help me find out this specific thing I dont know how to find out http://screencast.com/t/PUvesX4N

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agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2Once you find f'(x), plug in a to get the slope of the line, m. Then you want to get it in the form y=mx+b, by using the fact it passes through the point (a, f(a))

BTaylor
 one year ago
Best ResponseYou've already chosen the best response.1Do you know how to take the derivative? If so, then first take the derivative of the function, then evaluate it at the given a  this is "m", the slope of the tangent line. Now, evaluate the function at the given a. This we'll call "y1" The tangent line is: yy1 = m (xa)

Christos
 one year ago
Best ResponseYou've already chosen the best response.0Can please someone tell me what is a slope just so I get the bigger picture of whats going on?

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2Slope is the steepness of the line, or rate of change. Remember back in algebra, equations y=mx+b have a slope of m.

Christos
 one year ago
Best ResponseYou've already chosen the best response.0@BTaylor what do you mean by "Now, evaluate the function at the given a. " ?

BTaylor
 one year ago
Best ResponseYou've already chosen the best response.1so, for number 9, f(x) = 2x^2. The given "a" is 1. So evaluating the function at a means you plug in a for x, and get 2(1)^2, which is 2.

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2That means plug in x=1 (since a=1) into f = 2x^2

BTaylor
 one year ago
Best ResponseYou've already chosen the best response.1@agent0smith is right. To visualize this tangent line, click this link: http://www.wolframalpha.com/input/?t=crmtb01&f=ob&i=tangent%20line%20to%202x%5E2%20at%20x%3D1

BTaylor
 one year ago
Best ResponseYou've already chosen the best response.1the last one is right. y1 = 2.

Christos
 one year ago
Best ResponseYou've already chosen the best response.0so that's the answer?? y1 = 2 and I am done? Nothing else needed?

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2No... did you find the slope?

BTaylor
 one year ago
Best ResponseYou've already chosen the best response.1yes. because the derivative is 4x, evaluated at x=1 gives you 4(1) =4

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2So then put it in pointslope form: yy1 = m (xx1) where x1 = 1, y1= 2

Christos
 one year ago
Best ResponseYou've already chosen the best response.0I did all that and I got y1 = 2 in the end, I am done ?

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2Wait, no, where is your x going? yy1 = m (xa) y  2 = 4(x1)

Christos
 one year ago
Best ResponseYou've already chosen the best response.0then why y is not y too and had to be replaced

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2y is y. y2 = 4 (x1)

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2You're using point slope form to write the equation of a line: http://www.purplemath.com/modules/strtlneq2.htm

Christos
 one year ago
Best ResponseYou've already chosen the best response.0Nice! I see now! Thank you both! I wish I could give more medals!

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2Your line has a slope of m=4, and passes through the point (1, 2) then you just plug it into the point slope formula.

agent0smith
 one year ago
Best ResponseYou've already chosen the best response.2And again, this is what you have found: http://www.wolframalpha.com/input/?t=crmtb01&f=ob&i=tangent%20line%20to%202x%5E2%20at%20x%3D1
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