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Christos
 2 years ago
Limits,
Can you help me find out this specific thing I dont know how to find out
http://screencast.com/t/PUvesX4N
Christos
 2 years 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
 2 years 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
 2 years 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
 2 years 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
 2 years 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
 2 years 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
 2 years 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
 2 years ago
Best ResponseYou've already chosen the best response.2That means plug in x=1 (since a=1) into f = 2x^2

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

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

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

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

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

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

agent0smith
 2 years 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
 2 years ago
Best ResponseYou've already chosen the best response.0Nice! I see now! Thank you both! I wish I could give more medals!

agent0smith
 2 years 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
 2 years 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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