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Let 
g(x)=2^(-x^(3)+5x).
Below is Lila's attempt to write a formal justification for the fact that the equation 
g^(')(x)=-12 has a solution in the interval 
(1,2).
Is Lila's justification complete? If not, why?
Lila's justification:
Exponential and polynomial functions are differentiable and continuous at all points in their domain, and 
[1,2] is within 
g^(')s domain.
So, according to the mean value theorem, 
g^(')(x)=-12 must have a solution somewhere between 
x=1 and 
x=2.
Choose 1 answer:
(A) Yes, Lila's justification is complete.
(B) No, Lila didn't establish that the average rate of change of 
g over 
[1,2] is equal to -12 .
(C) No, Lila didn't establish that 
g is differentiable.

Let g(x)=2x3+5x g(x)=2^{-x^{3}+5 x} .\newlineBelow is Lila's attempt to write a formal justification for the fact that the equation g(x)=12 g^{\prime}(x)=-12 has a solution in the interval (1,2) (1,2) .\newlineIs Lila's justification complete? If not, why?\newlineLila's justification:\newlineExponential and polynomial functions are differentiable and continuous at all points in their domain, and [1,2] [1,2] is within gs g^{\prime} s domain.\newlineSo, according to the mean value theorem, g(x)=12 g^{\prime}(x)=-12 must have a solution somewhere between x=1 x=1 and x=2 x=2 .\newlineChoose 11 answer:\newline(A) Yes, Lila's justification is complete.\newline(B) No, Lila didn't establish that the average rate of change of g g over [1,2] [1,2] is equal to 12-12 .\newline(C) No, Lila didn't establish that g g is differentiable.

Full solution

Q. Let g(x)=2x3+5x g(x)=2^{-x^{3}+5 x} .\newlineBelow is Lila's attempt to write a formal justification for the fact that the equation g(x)=12 g^{\prime}(x)=-12 has a solution in the interval (1,2) (1,2) .\newlineIs Lila's justification complete? If not, why?\newlineLila's justification:\newlineExponential and polynomial functions are differentiable and continuous at all points in their domain, and [1,2] [1,2] is within gs g^{\prime} s domain.\newlineSo, according to the mean value theorem, g(x)=12 g^{\prime}(x)=-12 must have a solution somewhere between x=1 x=1 and x=2 x=2 .\newlineChoose 11 answer:\newline(A) Yes, Lila's justification is complete.\newline(B) No, Lila didn't establish that the average rate of change of g g over [1,2] [1,2] is equal to 12-12 .\newline(C) No, Lila didn't establish that g g is differentiable.
  1. Mean Value Theorem Application: Lila's justification relies on the Mean Value Theorem, which states that if a function is continuous on the closed interval [a,b][a, b] and differentiable on the open interval (a,b)(a, b), then there exists some cc in (a,b)(a, b) such that the function's derivative at cc is equal to the average rate of change of the function over [a,b][a, b].
  2. Function Continuity and Differentiability: To apply the Mean Value Theorem, Lila must first ensure that g(x)g(x) is continuous on [1,2][1, 2] and differentiable on (1,2)(1, 2). Since g(x)g(x) is an exponential function composed with a polynomial, it is continuous and differentiable everywhere in its domain, which includes [1,2][1, 2].
  3. Calculate Average Rate of Change: Next, Lila must calculate the average rate of change of g(x)g(x) over the interval [1,2][1, 2]. This is done by evaluating g(2)g(1)g(2) - g(1) and dividing by 212 - 1. However, Lila has not provided these calculations or shown that the average rate of change is equal to 12-12.
  4. Incomplete Justification: Without establishing that the average rate of change of g(x)g(x) over [1,2][1, 2] is 12-12, Lila cannot conclude that g(x)=12g'(x) = -12 for some xx in (1,2)(1, 2) based on the Mean Value Theorem. Therefore, Lila's justification is incomplete.

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