Calculate derivative and critical points: Calculate the derivative of y to find critical points.y=6x−12cosxdxdy=6+12sinxSet dxdy=0 to find critical points:6+12sinx=0sinx=−21
Solve for x: Solve sinx=−21 for x in the interval [−2π,π].x=−6π,67πBut 67π is not in the interval [−2π,π].So, the critical point is x=−6π.
Calculate second derivative: Calculate the second derivative to determine the nature of the critical point.dx2d2y=12cosxEvaluate dx2d2y at x=−6π:dx2d2y=12cos(−6π)=12×(3/2)=63Since 6\sqrt{3} > 0, the function has a relative minimum at x=−6π.
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