First, let's write the equation of the tangent line to the graph, to see what elements we have and what we have to find out.
y - f(1) = f'(1)*(x-1)
It's obvious that we have to calculate f(1), f'(x) and f'(1).
Let's begin with f(1).
We'll substitute x by 1, in the expression of the fucntion f(x).
f(1)=e^1/1
f(1)=e
Now, we'll calculate the first derivative of the function, using the product rule:
f'(x) = {[e^(x^2)]'*x - e^(x^2)*x'}/x^2
f'(x) = [2x*e^(x^2)*x - e^(x^2)]/x^2
We'll factorize and we'll get:
f'(x) = [e^(x^2)(2x^2 - 1)]/x^2
Now, we'll calculate f'(1).
f'(1) = [e^(1^2)(2 - 1)]/1^2
f'(1) = e
Now, we'll substitute the values for f(1) and f'(1), into equation of the tangent line, to verify if it's expression is the same with the one given into enunciation.
y - f(1) = f'(1)*(x-1)
y - e = e*(x-1)
We'll open the brackets and we'll get:
y - e =e*x - e
We'll reduce the similar terms:
y=e*x q.e.d.
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