IndietroBusiness Calculus Study Guidance: Limits, Continuity, Derivatives, Tangents, and Applications
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Q1. Evaluate
Background
Topic: Limits and Indeterminate Forms
This question tests your understanding of how to evaluate limits, especially when the expression initially appears to be indeterminate (like ).
Key Terms and Formulas:
Limit: The value a function approaches as the input approaches a certain point.
Indeterminate Form: An expression like that requires algebraic manipulation to resolve.
Step-by-Step Guidance
Substitute into the numerator and denominator to check if the limit is indeterminate.
If you get , factor the numerator to see if you can simplify the expression.
Cancel any common factors in the numerator and denominator.
Once simplified, substitute into the new expression to find the limit.
Try solving on your own before revealing the answer!
Final Answer: 20
Factoring the numerator gives . Cancel and substitute into to get $20$.
Q2. Is continuous at ? Justify your answer.
Background
Topic: Continuity of Piecewise Functions
This question tests your ability to determine continuity at a point for a piecewise-defined function.
Key Terms and Formulas:
Continuity: A function is continuous at if .
Piecewise Function: A function defined by different expressions for different intervals.
Step-by-Step Guidance
Find using the definition for .
Calculate using the expression for .
Compare the limit value to to determine continuity.
Try solving on your own before revealing the answer!
Final Answer: No, is not continuous at .
The limit as is $10h(5) = 10x \neq 5, so the function is not continuous at .
Q3. Use the formula for the derivative of a function at to find the derivative of .
Background
Topic: Derivatives and Differentiation Rules
This question tests your ability to apply basic differentiation rules to polynomial functions.
Key Terms and Formulas:
Derivative: represents the rate of change of with respect to .
Power Rule:
Step-by-Step Guidance
Identify the terms in : and .
Apply the power rule to each term separately.
Combine the results to write the derivative.
Try solving on your own before revealing the answer!
Final Answer:
Using the power rule, the derivative of is , and the derivative of is .
Q4. Find for .
Background
Topic: Differentiation of Products and Power Functions
This question tests your ability to differentiate products of power functions and constants.
Key Terms and Formulas:
Product Rule:
Power Rule:
Step-by-Step Guidance
Identify and .
Find the derivatives and using the power rule.
Apply the product rule to and .
Differentiate the constant (which becomes $0$).
Try solving on your own before revealing the answer!
Final Answer:
Apply the product rule and simplify the exponents and coefficients.
Q5. Differentiate
Background
Topic: Quotient Rule for Differentiation
This question tests your ability to use the quotient rule to differentiate a function where the numerator and denominator are both functions of .
Key Terms and Formulas:
Quotient Rule:
Exponential Rule:
Step-by-Step Guidance
Let and .
Find and using the power and exponential rules.
Apply the quotient rule formula.
Try solving on your own before revealing the answer!
Final Answer:
Apply the quotient rule and simplify the numerator and denominator.
Q6. Find the derivative of
Background
Topic: Product Rule for Differentiation
This question tests your ability to use the product rule to differentiate the product of two polynomial functions.
Key Terms and Formulas:
Product Rule:
Step-by-Step Guidance
Let and .
Find and using the power rule.
Apply the product rule formula.
Try solving on your own before revealing the answer!
Final Answer:
Apply the product rule and substitute the derivatives for and .
Q7. Differentiate
Background
Topic: Chain Rule for Differentiation
This question tests your ability to use the chain rule to differentiate a function raised to a negative power.
Key Terms and Formulas:
Chain Rule:
Power Rule:
Derivative of :
Step-by-Step Guidance
Let and .
Apply the power rule to .
Multiply by the derivative of using the chain rule.
Try solving on your own before revealing the answer!
Final Answer:
Apply the chain rule and power rule, then differentiate .
Q8. Find an equation of the tangent line to the function at the point .
Background
Topic: Tangent Lines and Derivatives
This question tests your ability to find the equation of a tangent line using the derivative at a specific point.
Key Terms and Formulas:
Tangent Line: A line that touches a curve at a single point and has the same slope as the curve at that point.
Slope of Tangent: at the given value.
Point-Slope Form:
Step-by-Step Guidance
Find for using the power rule.
Evaluate to get the slope at .
Use the point-slope form with the point and the slope found.
Try solving on your own before revealing the answer!
Final Answer:
The slope at is $32y - 16 = 32(x - 2)$.
Q9. A company finds that the cost and revenue, in dollars, of producing hundred items are given by and . Determine the rate at which the company's profit is changing when 900 items have been produced and sold.
Background
Topic: Marginal Analysis in Business Calculus
This question tests your ability to find the rate of change of profit, which is the derivative of the profit function with respect to .
Key Terms and Formulas:
Profit Function:
Marginal Profit:
Step-by-Step Guidance
Write the profit function .
Find and using the power rule.
Calculate .
Substitute (since 900 items means $x = 9$ hundred) into .
Try solving on your own before revealing the answer!
Final Answer:
The rate at which profit is changing when 900 items have been produced and sold is $38$ dollars per hundred items.
Q10. Differentiate
Background
Topic: Quotient Rule and Chain Rule for Differentiation
This question tests your ability to differentiate a quotient where the numerator involves both an exponential and a logarithmic function.
Key Terms and Formulas:
Quotient Rule:
Chain Rule:
Derivative of :
Derivative of :
Step-by-Step Guidance
Let and .
Find using the chain rule and logarithmic differentiation.
Find using the power rule.
Apply the quotient rule formula.
Try solving on your own before revealing the answer!
Final Answer:
Apply the quotient rule and simplify the numerator and denominator.