Write the equation of the line that is perpendicular to the line [tex]8y - 16 = 5x[/tex] through the point [tex](5, -5)[/tex].

A. [tex]y = -\frac{8}{5}x - 3[/tex]

B. [tex]y = \frac{5}{8}x + 3[/tex]

C. [tex]y = \frac{8}{5}x + 3[/tex]

D. [tex]y = -\frac{8}{5}x + 3[/tex]



Answer :

To determine the equation of a line that is perpendicular to the given line [tex]\(8y - 16 = 5x\)[/tex] and passes through the point [tex]\((5, -5)\)[/tex], follow these steps:

### Step 1: Rewrite the given equation in slope-intercept form
First, rearrange the given equation to the slope-intercept form, [tex]\(y = mx + b\)[/tex]:
[tex]\[ 8y - 16 = 5x \][/tex]
Add 16 to both sides:
[tex]\[ 8y = 5x + 16 \][/tex]
Divide every term by 8:
[tex]\[ y = \frac{5}{8}x + 2 \][/tex]
Thus, the slope (m) of the given line is [tex]\(\frac{5}{8}\)[/tex].

### Step 2: Determine the slope of the perpendicular line
The slope of a line perpendicular to another line is the negative reciprocal of the slope of the original line. Hence, the slope of the perpendicular line is:
[tex]\[ m_{\text{perpendicular}} = -\frac{1}{m} = -\frac{1}{\left( \frac{5}{8} \right)} = -\frac{8}{5} \][/tex]

### Step 3: Use the point-slope form to find the equation of the line
Now, use the point-slope form of the equation [tex]\( y - y_1 = m(x - x_1) \)[/tex] where [tex]\((x_1, y_1)\)[/tex] is the point [tex]\((5, -5)\)[/tex] and [tex]\(m\)[/tex] is [tex]\(-\frac{8}{5}\)[/tex]:
[tex]\[ y - (-5) = -\frac{8}{5}(x - 5) \][/tex]
This simplifies to:
[tex]\[ y + 5 = -\frac{8}{5}(x - 5) \][/tex]
Distribute the slope term on the right side:
[tex]\[ y + 5 = -\frac{8}{5}x + 8 \][/tex]
Subtract 5 from both sides to isolate [tex]\(y\)[/tex]:
[tex]\[ y = -\frac{8}{5}x + 8 - 5 \][/tex]
[tex]\[ y = -\frac{8}{5}x + 3 \][/tex]

### Conclusion
The equation of the line that is perpendicular to the given line and passes through the point [tex]\((5, -5)\)[/tex] is:
[tex]\[ y = -\frac{8}{5}x + 3 \][/tex]

Thus, the correct answer is [tex]\(\boxed{D}\)[/tex].

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