The derivative of the function f is defined by f′(x)=x2−5x−sin(3x+3). If f(−2)=−9, then use a calculator to find the value of f(4) to the nearest thousandth.Answer:
Q. The derivative of the function f is defined by f′(x)=x2−5x−sin(3x+3). If f(−2)=−9, then use a calculator to find the value of f(4) to the nearest thousandth.Answer:
Integrate f′(x): To find f(4), we need to integrate the derivative f′(x) to get the original function f(x). We will then use the initial condition f(−2)=−9 to find the constant of integration.Integrate f′(x)=x2−5x−sin(3x+3).The integral of x2 is (1/3)x3, the integral of −5x is (−5/2)x2, and the integral of f(4)0 is f(4)1 plus a constant f(4)2.So, f(4)3.
Use Initial Condition: Now we use the initial condition f(−2)=−9 to find the constant C. Substitute x=−2 into f(x) to get: −9=(1/3)(−2)3−(5/2)(−2)2+(1/3)cos(3(−2)+3)+C. Calculate the values: −9=(1/3)(−8)−(5/2)(4)+(1/3)cos(−3)+C. −9=−8/3−10+(1/3)cos(−3)+C.
Solve for Constant C: Simplify the equation to solve for C. −9=−38−10+31cos(−3)+C. Multiply all terms by 3 to clear the fraction: −27=−8−30+cos(−3)+3C. −27=−38+cos(−3)+3C. Add 38 to both sides: 11=cos(−3)+3C.
Calculate cos(−3): Use a calculator to find the value of cos(−3) to the nearest thousandth.cos(−3)≈0.990 (rounded to three decimal places).Now we have:11=0.990+3C.
Find Constant C: Solve for C.11−0.990=3C.10.010=3C.C=310.010.C≈3.337 (rounded to three decimal places).
Substitute x=4: Now that we have the constant C, we can write the original function f(x) as:f(x)=31x3−25x2+31cos(3x+3)+3.337.To find f(4), substitute x=4 into f(x):f(4)=31(4)3−25(4)2+31cos(3(4)+3)+3.337.Calculate the values:f(4)=31(64)−25(16)+31cos(15)+3.337.
Calculate cos(15): Simplify the equation to find f(4).f(4)=364−40+(31)cos(15)+3.337.Use a calculator to find the value of cos(15) to the nearest thousandth.cos(15)≈0.966 (rounded to three decimal places).Now we have:f(4)=364−40+(31)(0.966)+3.337.
Calculate f(4): Calculate the final value of f(4) to the nearest thousandth.f(4)=364−40+0.322+3.337.f(4)=21.333−40+0.322+3.337.f(4)=−18.667+0.322+3.337.f(4)=−18.345+3.337.f(4)=−15.008.Round to the nearest thousandth:f(4)≈−15.008.
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