SOLUTION: I am having a hard time with multiplying out (2+h)^3. I have tried to do (2+h)(2+h)(2+h) and did (2^2+2h+h^2)= (4+2h+h^2) . I am using this in Derivatives. So If f(x)=x^3 I

Algebra ->  Exponents -> SOLUTION: I am having a hard time with multiplying out (2+h)^3. I have tried to do (2+h)(2+h)(2+h) and did (2^2+2h+h^2)= (4+2h+h^2) . I am using this in Derivatives. So If f(x)=x^3 I       Log On


   



Question 494627: I am having a hard time with multiplying out (2+h)^3. I have tried to do
(2+h)(2+h)(2+h) and did (2^2+2h+h^2)= (4+2h+h^2) . I am using this in Derivatives.
So If f(x)=x^3 I have to find the tangent line of the equation through point (2,8).
So F'(2+h)= ((2+h))^3 Which is (4+2h+h^2)
Then F'(2)= (2)^3 Which is (8)
So then I take (4+2h+h^2)-(8)
and I get -4+2h+h^2/h Do you see my problem.
I have tried this so many different ways. Where am I making my error?

Found 2 solutions by richard1234, MathLover1:
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
You should definitely review how to multiply polynomials before pursuing a calculus course. To multiply out (2+h)^3, use the binomial theorem and expand.





This is assuming you want to evaluate where x=2.

Or, if you know that the derivative of x^3 is 3x^2, we can easily find the tangent line.





Hence we can write the tangent line in point-slope form


Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

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=8%2B8h%2B2h%5E2%2B4h%2B4h%5E2%2Bh%5E3

=8%2B12h%2B6h%5E2%2Bh%5E3...rearrange terms

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