Q. QuestionFind the equation of the line tangent to the graph of f(x)=x−1 at x=5.
Find Derivative of f(x): First, we need to find the derivative of f(x) to get the slope of the tangent line at x=5. f′(x)=(21)(x−1)−21⋅(1) by the chain rule.
Calculate Slope at x = 5: Now, plug in x=5 into f′(x) to find the slope at that point.f′(5)=(21)(5−1)−21=(21)(4)−21=(21)(21)=41.
Find y-coordinate at x=5: Next, find the y-coordinate of the point on the graph at x=5 by plugging it into f(x).f(5)=5−1=4=2.
Write Equation of Tangent Line: Now we have a point (5,2) and a slope 41. Use the point-slope form to write the equation of the tangent line.y−y1=m(x−x1), where m is the slope and (x1,y1) is the point.y−2=41(x−5).
Simplify Equation to Slope-Intercept Form: Finally, simplify the equation to get it into slope-intercept form, y=mx+b.y=41x−41(5)+2y=41x−45+48y=41x+43.