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What is the equation of the line that is perpendicular to [tex]$y = 2x + 3$[/tex] and passes through the point [tex]$(-4, 8)$[/tex]?

A. [tex][tex]$y = 2x + 16$[/tex][/tex]
B. [tex]$y = 2x - 20$[/tex]
C. [tex]$y = -\frac{1}{2}x$[/tex]
D. [tex][tex]$y = -\frac{1}{2}x + 6$[/tex][/tex]


Sagot :

To find the equation of the line that is perpendicular to [tex]\( y = 2x + 3 \)[/tex] and passes through the point [tex]\( (-4, 8) \)[/tex], follow these steps:

1. Identify the slope of the given line:
The given line is [tex]\( y = 2x + 3 \)[/tex]. The slope (m) of this line is 2.

2. Determine the slope of the perpendicular line:
The slope of a line that is perpendicular to another is the negative reciprocal of the original slope. The negative reciprocal of 2 is [tex]\( -\frac{1}{2} \)[/tex].

3. Use the point-slope form to find the y-intercept:
The point-slope form of a line equation is:
[tex]\[ y - y_1 = m(x - x_1) \][/tex]
Here, [tex]\( (x_1, y_1) \)[/tex] is the point [tex]\( (-4, 8) \)[/tex] and the slope (m) is [tex]\( -\frac{1}{2} \)[/tex].

Substitute the slope and the point into the equation:
[tex]\[ y - 8 = -\frac{1}{2}(x + 4) \][/tex]

4. Simplify the equation:
Expand the right side:
[tex]\[ y - 8 = -\frac{1}{2} x - 2 \][/tex]
Add 8 to both sides to solve for y:
[tex]\[ y = -\frac{1}{2} x - 2 + 8 \][/tex]
Simplify the right side:
[tex]\[ y = -\frac{1}{2} x + 6 \][/tex]

Therefore, the equation of the line that is perpendicular to [tex]\( y = 2x + 3 \)[/tex] and passes through the point [tex]\( (-4, 8) \)[/tex] is:
[tex]\[ y = -\frac{1}{2} x + 6 \][/tex]

The correct answer is:
[tex]\[ y = -\frac{1}{2} x + 6 \][/tex]