In: Math
Let f(x)=(x^2+1)*(2x-3)
Find the equation of the line tangent to the graph of f(x) at x=3.
Find the value(s) of x where the tangent line is horizontal.
a)
we have

put x = 3,



now,


the slope of the tangent line is,

slope at x = 3,



the equation of the tangent line is,

put the x0 = 3, y0 = 30 and m = 38,



b)
m=0 for the tangent line is horizontal,




we know that,

so,


hence no any real value of x where the tangent line is horizontal