Let h(x)=x3−9x2+7x and let c be the number that satisfies the Mean Value Theorem for h on the interval −3≤x≤6.What is c ?Choose 1 answer:(A) −1(B) 0(C) 3(D) 4
Q. Let h(x)=x3−9x2+7x and let c be the number that satisfies the Mean Value Theorem for h on the interval −3≤x≤6.What is c ?Choose 1 answer:(A) −1(B) 0(C) 3(D) 4
Mean Value Theorem: The Mean Value Theorem states that if a function f is continuous on the closed interval [a,b] and differentiable on the open interval (a,b), then there exists at least one number c in the interval (a,b) such that f′(c) is equal to the average rate of change of the function over [a,b]. The average rate of change is given by b−af(b)−f(a).
Calculate Endpoints: First, we need to find the values of h(x) at the endpoints of the interval. These are h(−3) and h(6). h(−3)=(−3)3−9(−3)2+7(−3)=−27−81−21=−129. h(6)=(6)3−9(6)2+7(6)=216−324+42=−66.
Calculate Average Rate: Now, we calculate the average rate of change of h(x) over the interval [−3,6].Average rate of change = 6−(−3)h(6)−h(−3)=6+3−66−(−129)=963=7.
Find Derivative: Next, we find the derivative of h(x), which is h′(x).h′(x)=dxd[x3−9x2+7x]=3x2−18x+7.
Apply Mean Value Theorem: According to the Mean Value Theorem, there exists a number c such that h′(c)=7 (the average rate of change we calculated).So we set the derivative equal to 7 and solve for c:3c2−18c+7=7.
Set Derivative Equal: Subtract 7 from both sides to set the equation to zero:3c2−18c=0.
Factor and Solve: Factor out the common term c:c(3c−18)=0.
Final Value of c: Set each factor equal to zero and solve for c:c=0 or 3c−18=0.
Final Value of c: Set each factor equal to zero and solve for c:c=0 or 3c−18=0.If 3c−18=0, then 3c=18 and c=6. However, c=6 is an endpoint of the interval and cannot be the value we are looking for according to the Mean Value Theorem. Therefore, the only possible value for c within the interval (−3,6) is c=0.