Part A: Explain why the [tex]\( x \)[/tex]-coordinates of the points where the graphs of the equations [tex]\( y=2^{-x} \)[/tex] and [tex]\( y=4^{x+3} \)[/tex] intersect are the solutions of the equation [tex]\( 2^{-x} = 4^{x+3} \)[/tex]. (4 points)

Part B: Make tables to find the solution to [tex]\( 2^{-x} = 4^{x+3} \)[/tex]. Take the integer values of [tex]\( x \)[/tex] only between [tex]\(-3\)[/tex] and [tex]\(3\)[/tex]. (4 points)

Part C: How can you solve the equation [tex]\( 2^{-x} = 4^{x+3} \)[/tex] graphically? (2 points)



Answer :

Let's tackle each part of the problem step by step.

### Part A: Explanation (4 points)

To understand why the [tex]\(x\)[/tex]-coordinates of the points where the graphs of the equations [tex]\(y = 2^{-x}\)[/tex] and [tex]\(y = 4^{x+3}\)[/tex] intersect are the solutions of the equation [tex]\(2^{-x} = 4^{x+3}\)[/tex], consider the following:

When two graphs intersect at a point, their [tex]\(y\)[/tex]-coordinates at that point are equal. This means that if the graphs of [tex]\(y = 2^{-x}\)[/tex] and [tex]\(y = 4^{x+3}\)[/tex] intersect at some point [tex]\((x, y)\)[/tex], then at that point,

[tex]\[2^{-x} = 4^{x+3}\][/tex]

Thus, solving the equation [tex]\(2^{-x} = 4^{x+3}\)[/tex] will give us the [tex]\(x\)[/tex]-coordinates where the two graphs intersect.

### Part B: Creating Tables (4 points)

To find the solution for the equation [tex]\(2^{-x} = 4^{x+3}\)[/tex] using integer values of [tex]\(x\)[/tex] between -3 and 3, we can create a table that shows the values of [tex]\(y\)[/tex] for both functions for each [tex]\(x\)[/tex]. The tables for [tex]\(y = 2^{-x}\)[/tex] and [tex]\(y = 4^{x+3}\)[/tex] are as follows:

[tex]\[ \begin{array}{|c|c|c|} \hline x & y = 2^{-x} & y = 4^{x+3} \\ \hline -3 & 8 & 1 \\ -2 & 4 & 4 \\ -1 & 2 & 16 \\ 0 & 1 & 64 \\ 1 & 0.5 & 256 \\ 2 & 0.25 & 1024 \\ 3 & 0.125 & 4096 \\ \hline \end{array} \][/tex]

From the table, we observe that the values of [tex]\(2^{-x}\)[/tex] and [tex]\(4^{x+3}\)[/tex] are equal when [tex]\(x = -2\)[/tex]. This point of equality suggests that [tex]\(x = -2\)[/tex] is a solution to the equation [tex]\(2^{-x} = 4^{x+3}\)[/tex].

### Part C: Graphical Solution (2 points)

To solve the equation [tex]\(2^{-x} = 4^{x+3}\)[/tex] graphically, you would follow these steps:

1. Plot the graph of the function [tex]\(y = 2^{-x}\)[/tex].
2. Plot the graph of the function [tex]\(y = 4^{x+3}\)[/tex] on the same axes.
3. Identify the points where the two graphs intersect.

The [tex]\(x\)[/tex]-coordinates of the intersection points are the solutions to the equation [tex]\(2^{-x} = 4^{x+3}\)[/tex]. From the table in Part B, we can see that the graphs intersect at [tex]\(x = -2\)[/tex], which confirms our solution.

---

This completes our detailed step-by-step solution to the problem.