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Ch. 1 - Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
1장, 문제 1.2.21

Composition of Functions


A balloon’s volume V is given by V = s² + 2s + 3 cm³, where s is the ambient temperature in °C. The ambient temperature s at time t minutes is given by s = 2t − 3 °C. Write the balloon’s volume V as a function of time t.

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1
Identify the given functions: The volume of the balloon is given by \( V = s^2 + 2s + 3 \) and the ambient temperature is given by \( s = 2t - 3 \).
Recognize that you need to find the composition of functions, specifically \( V(s(t)) \), which means substituting the expression for \( s \) into the volume function \( V \).
Substitute \( s = 2t - 3 \) into the volume function \( V = s^2 + 2s + 3 \). This gives \( V = (2t - 3)^2 + 2(2t - 3) + 3 \).
Expand the expression \( (2t - 3)^2 \) using the formula \( (a - b)^2 = a^2 - 2ab + b^2 \). This results in \( 4t^2 - 12t + 9 \).
Combine all terms: \( V = 4t^2 - 12t + 9 + 4t - 6 + 3 \). Simplify the expression to write the volume \( V \) as a function of time \( t \).

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
2m
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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Composition of Functions

Composition of functions involves combining two functions to create a new function. In this case, we have two functions: the volume V as a function of temperature s, and the temperature s as a function of time t. To find V as a function of t, we substitute the expression for s into the equation for V, effectively creating a new function that relates volume directly to time.
추천 영상:
3:48
Evaluate Composite Functions - Special Cases

Quadratic Functions

A quadratic function is a polynomial function of degree two, typically expressed in the form V = ax² + bx + c. In the given volume equation V = s² + 2s + 3, the variable s is raised to the second power, indicating that the volume changes in a parabolic manner with respect to temperature. Understanding the properties of quadratic functions, such as their vertex and axis of symmetry, is essential for analyzing their behavior.
추천 영상:
6:04
Introduction to Polynomial Functions

Substitution Method

The substitution method is a technique used in algebra and calculus to simplify expressions or solve equations by replacing a variable with another expression. In this problem, we substitute the expression for s (temperature) into the volume equation V. This method allows us to express V solely in terms of t (time), facilitating the analysis of how the balloon's volume changes over time.
추천 영상:
04:27
Substitution With an Extra Variable