A degree 5 polynomial has: negative leading coefficient, zeros at \( x = -2 \) (order 2), \( x = 0 \) (order 1), \( x = 3 \) (order 2), and \( f(1) = 12 \). Find the equation.
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Question 9 [4 marks]
Without graphing technology, factor \( g(x) = x^4 - 8x^2 + 12 \) completely and determine the number of x-intercepts. Show all reasoning.
A quartic function has turning points at \( x = -2, 1, 4 \) and is positive for all \( x \). Is this possible? Explain your reasoning with a sketch if applicable.
A polynomial passes through \( (0,0), (2,0), (5,0) \) with degree 4 and positive leading coefficient. Between which pairs of zeros must there be a turning point? Explain.
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Part C: Communication [15 marks]
Question 12 [4 marks]
A student claims: "A polynomial of degree 4 always has exactly 3 turning points." Is this correct? Provide a clear explanation with an example and counterexample. Write the correct statement.
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Question 13 [4 marks]
Explain the difference between the graph at a zero of order 1, order 2, and order 3. Include a sketch for each and describe the behaviour.
Describe a step-by-step method for sketching a polynomial given in factored form. Cover: intercepts, end behaviour, multiplicity, and additional points.
A student calculated the average rate of change of \( f(x)=x^2 \) on \([1,4]\) as 5 and said the instantaneous rate at \( x=2.5 \) is also 5. Is the ARoC correct? Is the reasoning about IRoC correct? Estimate the actual IRoC at \( x=2.5 \).
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Part D: Application [15 marks]
Question 16 [4 marks]
A box is made by cutting squares of side \( x \) from each corner of a 20cm × 30cm cardboard. Write \( V(x) \), state the domain in context, and determine the degree.
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Question 17 [4 marks]
Bacteria population: \( P(t) = -0.5t^4 + 8t^3 - 36t^2 + 200 \). Find: a) initial population, b) ARoC from \( t=0 \) to \( t=4 \), c) interpret in context.
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Question 18 [3 marks]
Roller coaster: \( h(x) = -0.001(x+10)^2(x-20)(x-50)^2 \). Where is it at ground level? Where does it touch and return vs pass through?
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Question 19 [4 marks]
Profit: \( P(x) = -2x^3 + 15x^2 - 24x \). For what production levels is profit positive? Estimate the ARoC on \([1,3]\). Should the company produce 4000 items?
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Evaluation Rubric
Level
Description
%
4
Thorough, insightful, high degree of effectiveness