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Student’s name Professor’s name Course Date HOME WORK (1) The length of a 12-foot by 8-foot rectangle is increasing at a rate of 3 feet per second and the width is decreasing at 2 feet per second (see figure below). How fast is the perimeter changing? Solution Given dl/dt=3 And dw/dt=-2 Then dp when l=12 ft and w=8ft Perimeter= 2l+2w Dp/dt=d/dt{2l+2w} =2dl/dt+2dw/dt=2(3)+2(-2) =2 ft/sec How fast is the area changing? Solution Given dl/dt=3, dw/dt=-2 Da/dt when l=12 ft , w=8ft Area=lxwDa/dt=d/dt{lxw} =Dl/dt*w+dw/dt*l =3(8)+ 12(-2) =0 ft2/sec (c) Find all critical points and local extremes of the following function on the given intervals. f (x) = 2-x3 on Solution To find the critical points, take derivative: f’(x)=-3x2 f’(X)= 0 0=-3x2 X=0 For absolute minima and maxima; f(0)=2-(0)3=2 f(-2)=2-(-2)3=10 f(1)=2-(1)3=1 Therefore: abs minima =1 at x=1 Abs maxima=10 at x=-2 (d) Calculate the limits of the following limx→0x+5x2 Solution Divide both numerator and denominator by x2 =lim x->0 1/x+5/x2 Since we have 0 in the denominator, the limit=0 (e) evaluate A'(x) at x = 1, 2, and 3. A(x) = -3x 2t dtSolution =d/dx(t2) At x=1; (12)-(-32) =-5 At x=2; (22)-(-32) =-2 At x=3;(32)-(-32) =12 (f) . Let A(x) represent the area bounded by the graph and the horizontal axis and vertical lines at t=0 and t=x for the graph in Fig. 25. Evaluate A(x) for x = 1, 2, 3, 4, and 5. Solution At X=1; A=1*1= 1unit2 X=2; A=1+1.5=2.5 units2 X=3; A=2.5+(1*2)= 4.5 units2 X=4; A=4.5+1.5=6 units2 X=5; A=6+1=7 units2 Work cited Anton, Howard, Irl Bivens, and Stephen
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