Linear Approximation w/ No Variables

[krystalleigh]

I'm stumped on this one. The question is as follows:

Use linear approximation to approximate: 7(3.02)^2 + 2(3.02) + 12 <---- all under a square root

I'm not really sure where to start with this. I think i'm confused because there are no variables. I tried finding the first derivative which is:

1/2[7(3.02)^2 + 2(3.02) + 12]^-1/2 which equals approx 0.056 but i'm not sure what to do with that information. The linear approximation formula I have is f(x)=f(a)+f'(a)(x-a). Thanks!

 

[tkhunny]

\(\displaystyle f(x) = \sqrt{7\cdot x^{2} + 2\cdot x + 12}\)

x = 3

a = 0.02

Are you sure it's not f(x)=f(x)+f'(x)(x-a)?