1. The problem statement, all variables and given/known data Given f(x)=sqrt(2x+2) Question : Find the linear approximation of f(x) at a=7 AND use it to approximate sqrt(18). 2. Relevant equations L(x)=f(a)+f'(a)(x-a) 3. The attempt at a solution Using the linear approximation formula I am getting the value 6.75, but when I checked with calculator the value of sqrt(18) is 4.2426.... Did my approximation is wrong?