The function f is defined by f(x)=x3+3cos(2x−4). Use a calculator to write the equation of the line tangent to the graph of f when x=−1. You should round all decimals to 3 places.Answer:
Q. The function f is defined by f(x)=x3+3cos(2x−4). Use a calculator to write the equation of the line tangent to the graph of f when x=−1. You should round all decimals to 3 places.Answer:
Calculate Derivative: To find the equation of the tangent line at x=−1, we first need to calculate the derivative of f(x), which will give us the slope of the tangent line at any point x. The derivative of f(x)=x3+3cos(2x−4) is f′(x)=3x2−6sin(2x−4).
Find Slope at x=−1: Now we need to evaluate the derivative at x=−1 to find the slope of the tangent line at that point.f′(−1)=3(−1)2−6sin(2(−1)−4)=3−6sin(−6).Using a calculator, we find that sin(−6)≈−0.2794 (rounded to four decimal places for intermediate calculation).
Find y-coordinate at x=−1: Now we plug the value of sin(−6) into the derivative to get the slope at x=−1.f′(−1)=3−6(−0.2794)≈3+1.6764=4.6764 (rounded to four decimal places for intermediate calculation). We round the slope to three decimal places as instructed: slope ≈4.676.
Use Point-Slope Form: Next, we need to find the y-coordinate of the point on the graph of f(x) at x=−1 to use it in the point-slope form of the equation of the tangent line.f(−1)=(−1)3+3cos(2(−1)−4)=−1+3cos(−6).Using a calculator, we find that cos(−6)≈0.9602 (rounded to four decimal places for intermediate calculation).
Convert to Slope-Intercept Form: Now we plug the value of cos(−6) into the function to get the y-coordinate at x=−1.f(−1)=−1+3(0.9602)≈−1+2.8806=1.8806 (rounded to four decimal places for intermediate calculation). We round the y-coordinate to three decimal places as instructed: y-coordinate ≈1.881.
Convert to Slope-Intercept Form: Now we plug the value of cos(−6) into the function to get the y-coordinate at x=−1.f(−1)=−1+3(0.9602)≈−1+2.8806=1.8806 (rounded to four decimal places for intermediate calculation). We round the y-coordinate to three decimal places as instructed: y-coordinate ≈1.881.We now have the slope of the tangent line (m≈4.676) and a point on the tangent line (x=−1, y≈1.881). We can use the point-slope form of the equation of a line to write the equation of the tangent line: y−y1=m(x−x1). Substituting the known values, we get: y−1.881=4.676(x−(−1)).
Convert to Slope-Intercept Form: Now we plug the value of cos(−6) into the function to get the y-coordinate at x=−1.f(−1)=−1+3(0.9602)≈−1+2.8806=1.8806 (rounded to four decimal places for intermediate calculation). We round the y-coordinate to three decimal places as instructed: y-coordinate ≈1.881.We now have the slope of the tangent line (m≈4.676) and a point on the tangent line (x=−1, y≈1.881). We can use the point-slope form of the equation of a line to write the equation of the tangent line: y−y1=m(x−x1). Substituting the known values, we get: y−1.881=4.676(x−(−1)).Simplify the equation to get it into the slope-intercept form y=mx+b. x=−10. Now, add x=−11 to both sides to isolate x=−12. x=−13.
Convert to Slope-Intercept Form: Now we plug the value of cos(−6) into the function to get the y-coordinate at x=−1.f(−1)=−1+3(0.9602)≈−1+2.8806=1.8806 (rounded to four decimal places for intermediate calculation). We round the y-coordinate to three decimal places as instructed: y-coordinate ≈1.881.We now have the slope of the tangent line (m≈4.676) and a point on the tangent line (x=−1, y≈1.881). We can use the point-slope form of the equation of a line to write the equation of the tangent line: y−y1=m(x−x1). Substituting the known values, we get: y−1.881=4.676(x−(−1)).Simplify the equation to get it into the slope-intercept form y=mx+b. x=−10. Now, add x=−11 to both sides to isolate x=−12. x=−13.Combine like terms to get the final equation of the tangent line. x=−14. We round the constant term to three decimal places as instructed: x=−15.
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