AA x,y,z in RR f(x+y+z) = f(x)f(y)f(z)!=0 & f(2)=5 , f'(0)=2 then find the value of f'(2) ? Calculus Applications of Derivatives Using the Tangent Line to Approximate Function Values 1 Answer Cesareo R. Oct 13, 2016 f'(2)=pm10 Explanation: f(x+0+0)=f(x)f(0)^2=f(x)->f(0)^2= 1 f(x+delta+0)=f(x)f(delta)f(0) lim_(delta->0)(f(x+delta)-f(x-delta))/(2delta) = lim_(delta->0)(f(x)f(delta)f(0)-f(x)f(-delta)f(0))/(2delta) = = f(x)f(0)lim_(delta->0)(f(delta)-f(-delta))/(2delta) = f(x)f(0)f'(0) but f(0)=pm1 and f'(0) =2 so f'(x) = f(0)f'(0)f(x) = pm2f(x) and finally f'(2)=pm10 Note: (f'(x))/f(x)=pm1/2 then f(x)=C_0e^(pm x/2) Answer link Related questions How do you find the linear approximation of (1.999)^4 ? How do you find the linear approximation of a function? How do you find the linear approximation of f(x)=ln(x) at x=1 ? How do you find the tangent line approximation for f(x)=sqrt(1+x) near x=0 ? How do you find the tangent line approximation to f(x)=1/x near x=1 ? How do you find the tangent line approximation to f(x)=cos(x) at x=pi/4 ? How do you find the tangent line approximation to f(x)=e^x near x=0 ? How do you use the tangent line approximation to approximate the value of ln(1003) ? How do you use the tangent line approximation to approximate the value of ln(1.006) ? How do you use the tangent line approximation to approximate the value of ln(1004) ? See all questions in Using the Tangent Line to Approximate Function Values Impact of this question 1924 views around the world You can reuse this answer Creative Commons License