Math Problem Statement

5. Explain why the values of the exponential expression 3^x will eventually overtake the values of the quadratic expression 10x^2. 6. A baseball travels d meters t seconds after being dropped from the top of a building. The distance traveled by the baseball can be modeled by the equation d = 5t^2. Which graph could represent this situation? Explain how you know. 7. Consider a function q defined by q(x) = x^2. Explain why negative values are not included in the range of q.

Solution

Let's analyze and solve the questions from the image you provided. Here’s a breakdown for each problem:


Question 5:

Explain why the values of the exponential expression 3x3^x will eventually overtake the values of the quadratic expression 10x210x^2.

Explanation:

  • Exponential functions grow much faster than polynomial functions as xx increases.
  • For smaller values of xx, 3x3^x may be less than 10x210x^2, since the quadratic 10x210x^2 grows quickly for small values of xx.
  • However, as xx \to \infty, the base of the exponential function (33) is repeatedly multiplied by itself, leading to much larger growth compared to the quadratic (x2x^2), which only grows by squaring xx.
  • Mathematically, the growth of an exponential function is proportional to its current value, making it faster than the polynomial, whose growth is proportional to a lower power of xx.

Question 6:

A baseball travels dd meters tt seconds after being dropped from the top of a building. The distance traveled by the baseball can be modeled by d=5t2d = 5t^2. Which graph represents this situation?

  • The equation d=5t2d = 5t^2 describes a quadratic relationship between distance dd and time tt, meaning the graph should show a curve where dd increases more rapidly as tt increases.
  • Comparing Graph A and Graph B:
    • Graph A shows a linear relationship, which is incorrect because d=5t2d = 5t^2 is quadratic, not linear.
    • Graph B shows a curve, consistent with the quadratic nature of d=5t2d = 5t^2.
  • Correct Answer: Graph B represents this situation.

Why:

  • For each second that passes, the increase in distance becomes larger due to the squared term (t2t^2).

Question 7:

Consider a function qq defined by q(x)=x2q(x) = x^2. Explain why negative values are not included in the range of qq.

Explanation:

  • The range of a function refers to the set of all possible output values.
  • For q(x)=x2q(x) = x^2:
    • Squaring any real number xx (positive, negative, or zero) results in a non-negative value.
    • For example:
      • (2)2=4(-2)^2 = 4
      • 02=00^2 = 0
      • 22=42^2 = 4
    • There are no values of xx that produce a negative result when squared.
  • Therefore, the range of q(x)=x2q(x) = x^2 is [0,)[0, \infty), and negative values cannot be included.

Follow-Up Questions:

  1. What happens when the base of an exponential function (like 3x3^x) is less than 1? How does this affect its growth?
  2. Can you identify the vertex of d=5t2d = 5t^2 and explain its physical meaning in the context of the problem?
  3. How does the function q(x)=x2q(x) = x^2 change when shifted vertically (e.g., q(x)=x2+3q(x) = x^2 + 3)? What happens to its range?
  4. Why does the rate of change in 3x3^x increase as xx increases, but the rate of change in 10x210x^2 stays constant for large values of xx?
  5. If d(t)=5t2d(t) = 5t^2, how would the graph change if the coefficient of t2t^2 were different (e.g., d(t)=2t2d(t) = 2t^2)?

Tip:

Always compare the growth rates of functions by calculating or estimating their derivatives—this provides insight into how quickly each function changes relative to the other. For example, the derivative of 3x3^x is proportional to 3x3^x, but the derivative of 10x210x^2 is linear.

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Math Problem Analysis

Mathematical Concepts

Exponential growth
Quadratic growth
Range of a function
Quadratic functions and graphs

Formulas

Exponential expression: 3^x
Quadratic expression: 10x^2
Quadratic equation: d = 5t^2
Function definition: q(x) = x^2

Theorems

Exponential growth surpassing polynomial growth
Properties of quadratic functions
Range of functions

Suitable Grade Level

Grades 8-10