Nathaniel B. answered 01/07/20
Experienced Calculus Tutor with Concept-Based and Visual Approaches
To find the equation of the tangent line, you first find the slope of the line at the given point (x=3).
To do this, take the derivative and plug in 3:
f'(x)=4x-1 so f'(3)=11
You then plug this slope into the formula for a line, which is:
Y2-Y1= slope(x2-x1) where x1 and y1 represent any point along the line. We have an x value, we have the slope, so now we just need a corresponding y value. Plug 3 into the original equation and you'll get 19. So the equation is:
Y-19= 11(x-3)
Simplify:
Y-19=11x-33
Y=11x-14
The Answer is A