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

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agent0smithBest ResponseYou've already chosen the best response.2
Once 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))
 10 months ago

BTaylorBest ResponseYou've already chosen the best response.1
Do 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)
 10 months ago

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

agent0smithBest ResponseYou've already chosen the best response.2
Slope is the steepness of the line, or rate of change. Remember back in algebra, equations y=mx+b have a slope of m.
 10 months ago

ChristosBest ResponseYou've already chosen the best response.0
@BTaylor what do you mean by "Now, evaluate the function at the given a. " ?
 10 months ago

BTaylorBest ResponseYou've already chosen the best response.1
so, 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.
 10 months ago

agent0smithBest ResponseYou've already chosen the best response.2
That means plug in x=1 (since a=1) into f = 2x^2
 10 months ago

BTaylorBest 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
 10 months ago

BTaylorBest ResponseYou've already chosen the best response.1
the last one is right. y1 = 2.
 10 months ago

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

agent0smithBest ResponseYou've already chosen the best response.2
No... did you find the slope?
 10 months ago

BTaylorBest ResponseYou've already chosen the best response.1
yes. because the derivative is 4x, evaluated at x=1 gives you 4(1) =4
 10 months ago

agent0smithBest ResponseYou've already chosen the best response.2
So then put it in pointslope form: yy1 = m (xx1) where x1 = 1, y1= 2
 10 months ago

ChristosBest ResponseYou've already chosen the best response.0
I did all that and I got y1 = 2 in the end, I am done ?
 10 months ago

agent0smithBest ResponseYou've already chosen the best response.2
Wait, no, where is your x going? yy1 = m (xa) y  2 = 4(x1)
 10 months ago

ChristosBest ResponseYou've already chosen the best response.0
then why y is not y too and had to be replaced
 10 months ago

agent0smithBest ResponseYou've already chosen the best response.2
y is y. y2 = 4 (x1)
 10 months ago

agent0smithBest ResponseYou've already chosen the best response.2
You're using point slope form to write the equation of a line: http://www.purplemath.com/modules/strtlneq2.htm
 10 months ago

ChristosBest ResponseYou've already chosen the best response.0
Nice! I see now! Thank you both! I wish I could give more medals!
 10 months ago

agent0smithBest ResponseYou've already chosen the best response.2
Your line has a slope of m=4, and passes through the point (1, 2) then you just plug it into the point slope formula.
 10 months ago

agent0smithBest ResponseYou've already chosen the best response.2
And 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
 10 months ago
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