For #f(x) =-3x^5-8x^3+4x^2#, what is the equation of the line tangent to #x =1 #?

1 Answer
Oct 29, 2015

#y=-31x+24#

Explanation:

To find the equation of the line tangent to the graph of #f(x) =-3x^5-8x^3+4x^2#, we need a point on the line and the slope of the line.

If the line is to be tangent to the curve at the point where #x=1#, then the tangent line includes #(1,f(1))#.

#f(1) = -3-8+4 = -7#, so the point #(1,-7)# is on the line.

We find the slope of the line using the derivative:

#f'(x) = -15x^4-24x^2+8x#.

At the point where #x=1#, the slope of the tangent line is #f'(1) = -15-24+8--31#

The slope intercept equation of the line through #(1,-7)# with slope #m=-31# is

#y=-31x+24#