The function f is defined by f(x)=x2−5cos(2x). Use a calculator to write the equation of the line tangent to the graph of f when x=3. You should round all decimals to 3 places.Answer:
Q. The function f is defined by f(x)=x2−5cos(2x). Use a calculator to write the equation of the line tangent to the graph of f when x=3. You should round all decimals to 3 places.Answer:
Calculate Derivative of f: To find the equation of the tangent line to the graph of f at x=3, we need to calculate the derivative of f, which will give us the slope of the tangent line at that point. The derivative of f with respect to x is f′(x)=2x−5⋅derivative of cos(2x). The derivative of cos(2x) with respect to x is −sin(2x)⋅2 (using the chain rule). Therefore, f′(x)=2x−5⋅(−2sin(2x))=2x+10sin(2x).
Evaluate Derivative at x=3: Now we need to evaluate the derivative at x=3 to find the slope of the tangent line. So we calculate f′(3)=2(3)+10sin(2⋅3). Using a calculator, we find that sin(6) is approximately −0.279. Therefore, f′(3)≈6+10(−0.279)=6−2.79=3.21.
Find y-coordinate at x=3: Next, we need to find the y-coordinate of the point on the graph of f where x=3. We do this by evaluating f(3)=32−5cos(2⋅3). Using a calculator, we find that cos(6) is approximately 0.960. Therefore, f(3)≈9−5(0.960)=9−4.8=4.2.
Write Equation of Tangent Line: With the slope of the tangent line m=3.21 and the point on the graph (3,4.2), we can use the point-slope form of the equation of a line to write the equation of the tangent line. The point-slope form is y−y1=m(x−x1), where m is the slope and (x1,y1) is the point on the line. Plugging in our values, we get y−4.2=3.21(x−3).
Convert to Slope-Intercept Form: Finally, we simplify the equation to put it in slope-intercept formy=mx+b. We distribute the slope on the right side of the equation and then add 4.2 to both sides to solve for y. y−4.2=3.21x−9.63. Adding 4.2 to both sides gives us y=3.21x−9.63+4.2. Simplifying further, y=3.21x−5.43.
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