Math CentralQuandaries & Queries


Question from Amanda, a student:

an equation of the line tangent to y=x^3+3x^2+2 at its point of inflection is
(A) y=-6x-6
(B) y= -3x+1
(C) y= 2x+10
(D) y=3x-1
(E) y=4x+1

Hi Amanda,

Use the second derivative to locate the inflection point. Use the first derivative to find the slope of the tangent line to the curve at this point. Compare this slope to the slopes of the 4 candidate lines. What did you learn?


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