Select the correct answer.

Suppose the following function is graphed:

[tex]\[ y = \frac{B}{5} x + 4 \][/tex]

On the same grid, a new function is graphed. The new function is represented by the following equation:

[tex]\[ y = -\frac{5}{8} x + 8 \][/tex]

Which of the following statements about these graphs is true?

A. The graphs intersect at [tex]\((0,8)\)[/tex].
B. The graph of the original function is perpendicular to the graph of the new function.
C. The graph of the original function is parallel to the graph of the new function.
D. The graphs intersect at [tex]\((0,4)\)[/tex].



Answer :

Let's analyze and solve the problem step-by-step to determine which statement about the graphs is true.

### Step 1: Identify the slope and intercept of the original function
The original function is given by:
[tex]\[ y = \frac{B}{5} x + 4 \][/tex]

To find the slope, we need to look at the coefficient of [tex]\( x \)[/tex]:
[tex]\[ \text{slope of the original function} = \frac{B}{5} \][/tex]

The y-intercept of the original function is:
[tex]\[ 4 \][/tex]

### Step 2: Identify the slope and intercept of the new function
The new function is given:
[tex]\[ y = -\frac{5}{8} x + 8 \][/tex]

The slope is:
[tex]\[ -\frac{5}{8} \][/tex]

The y-intercept of the new function is:
[tex]\[ 8 \][/tex]

### Step 3: Determine if the lines are parallel
Two lines are parallel if their slopes are equal. So we compare the slopes:
[tex]\[ \frac{B}{5} \text{ and } -\frac{5}{8} \][/tex]
Clearly, the two slopes are not equal unless:
[tex]\[ \frac{B}{5} = -\frac{5}{8} \][/tex]

This equation has no integer solution for [tex]\( B \)[/tex], so the lines are not parallel.

### Step 4: Determine if the lines are perpendicular
Two lines are perpendicular if the product of their slopes is [tex]\(-1\)[/tex]:
[tex]\[ \left(\frac{B}{5}\right) \times \left(-\frac{5}{8}\right) = -1 \][/tex]

Simplifying the product:
[tex]\[ \frac{-5B}{40} = -1 \][/tex]
[tex]\[ \frac{-B}{8} = -1 \][/tex]
[tex]\[ B = 8 \][/tex]

So, if [tex]\( B = 8 \)[/tex], then the two lines are perpendicular.

### Step 5: Identify intersection points
The lines intersect where:
[tex]\[ \frac{B}{5}x + 4 = -\frac{5}{8}x + 8 \][/tex]

Substituting [tex]\( B = 8 \)[/tex]:
[tex]\[ \frac{8}{5}x + 4 = -\frac{5}{8}x + 8 \][/tex]

To find [tex]\( x \)[/tex]:
[tex]\[ \frac{8}{5}x + \frac{5}{8}x = 8 - 4 \][/tex]
[tex]\[ (\frac{64}{40} + \frac{25}{40}) x = 4 \][/tex]
[tex]\[ \frac{89}{40} x = 4 \][/tex]
[tex]\[ x = \frac{4 \times 40}{89} = \frac{160}{89} \][/tex]

Substituting [tex]\( x \)[/tex] back to find [tex]\( y \)[/tex]:
[tex]\[ y = \frac{8}{5} \times \frac{160}{89} + 4 \][/tex]
[tex]\[ y = \left( \frac{1280}{445} + \frac{1780}{445} \right) \][/tex]
[tex]\[ y = 4 \][/tex]

Since we have calculated [tex]\( x \approx 1.8 \)[/tex], clearly it doesn’t satisfy our intersection points at specific options a and intersection at 0,8 also doesn’t hold true for [tex]\( x = 0 \)[/tex].

### Conclusion:
After analyzing all options and accounting for the perpendicular nature derived when [tex]\( B=8 \)[/tex], we have:

B. The graph of the original function is perpendicular to the graph of the new function is correct answer.

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