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

1. Identify the slope of the given line:
The given equation is in slope-intercept form [tex]\( y = mx + b \)[/tex], where [tex]\( m \)[/tex] is the slope. For the line [tex]\( y = 2x + 3 \)[/tex], the slope [tex]\( m \)[/tex] is 2.

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

3. Use the point-slope form of the equation of a line:
The point-slope form of the equation of a line is given by:
[tex]\[ y - y_1 = m(x - x_1) \][/tex]
Here, [tex]\((x_1, y_1)\)[/tex] is a point on the line and [tex]\( m \)[/tex] is the slope. We know that the perpendicular line passes through the point [tex]\((-4, 8)\)[/tex] and its slope is [tex]\(-\frac{1}{2}\)[/tex]. Substituting these values into the point-slope form gives:
[tex]\[ y - 8 = -\frac{1}{2}(x + 4) \][/tex]

4. Simplify the equation to slope-intercept form:
We now simplify the equation to get it in the form [tex]\( y = mx + b \)[/tex]:
[tex]\[ y - 8 = -\frac{1}{2}(x + 4) \][/tex]
[tex]\[ y - 8 = -\frac{1}{2}x - 2 \][/tex]
[tex]\[ y = -\frac{1}{2}x - 2 + 8 \][/tex]
[tex]\[ y = -\frac{1}{2}x + 6 \][/tex]

Hence, 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]\[ \boxed{y = -\frac{1}{2} x + 6} \][/tex]