Answer to Question #158939 in Calculus for effa

Question

find the slope of the tangent line to f(x)=x² + 2x at x=3

Answer 1

Solution:

Given: $f(x)=x^2+2x$ ...(i)

Slope of tangent is $f'(x)$

So, we find derivative of given $f(x)$

On differentiating (i) w.r.t $x$

$f'(x)=2x+2$

Putting $x=3$ in $f'(x)$ , we get,

$f'(3)=2(3)+2=6+2=8$

Answer: 8