Find the linear approximation to f(x) = sqrt(1-4x) at x=-2

I keep getting (-2/3)*x +(13/3) as the answer, but it is wrong?

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- Nov 12th 2009, 02:01 PMVelvet LoveLinear Approximation
Find the linear approximation to f(x) = sqrt(1-4x) at x=-2

I keep getting (-2/3)*x +(13/3) as the answer, but it is wrong? - Nov 12th 2009, 02:07 PMskeeter
- Nov 12th 2009, 02:12 PMartvandalay11
yes you took the derivative correctly, but it looks like something went wrong when you brought 3 over from the left hand side, or maybe when you multiplied through by $\displaystyle -\frac{2}{3}$

- Nov 12th 2009, 02:12 PMVelvet Love
Can you show me the steps? I do everything by the book, and i still get that answer.

- Nov 12th 2009, 02:14 PMartvandalay11