Wednesday, March 25, 2015

What is the equation of the tangent line to the curve f(x)=3x^2+1, at the point x=1?

We'll recall the fact that the derivative of a function at
a given point is represented by the value of the slope of the tangent line at the
curve.


The equation of the tangent line, in the point x =
1 is:


y - f(1) =
f'(1)(x-1)


We'll calculate f(1), by substituting x by 1 in
the expression of the function:


f(1) = 3*1^2 +
1


f(1) = 3 + 1


f(1) =
4


To calculate f'(1), first we'll have to differentiate the
given function with respect to x:


f'(x) = (3x^2 +
1)'


f'(x) = 6x


Now, we'll
replace x by 1 in the expression of the first
derivative:


f'(1) = 6


Now,
we'll substitute f(1) and f'(1) in the expression of the equation of the tangent
line:


y - f(1) = f'(1)(x-1)


y
- 4 = 6(x - 1)


We'll remove the
brackets:


y - 4 = 6x - 6


We'll
add 6 both sides:


y = 6x - 6 +
4


y = 6x - 2


The
equation of the tangent line, to the curve f(x) = 3x^2 + 1, is: y = 6x -
2.

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