What is the equation of a line that is perpendicular to [tex]y=2x+4[/tex] and passes through the point [tex]\((4, 6)\)[/tex]?

A. [tex]y=-\frac{1}{2}x+8[/tex]
B. [tex]y=-\frac{1}{2}x+6[/tex]
C. [tex]y=-\frac{1}{2}x+4[/tex]
D. [tex]y=\frac{1}{2}x+4[/tex]



Answer :

To determine the equation of a line that is perpendicular to the line [tex]\( y = 2x + 4 \)[/tex] and passes through the point [tex]\( (4, 6) \)[/tex], we need to follow these steps:

### Step 1: Find the slope of the given line

The given line is [tex]\( y = 2x + 4 \)[/tex]. The slope of this line (in the format [tex]\( y = mx + b \)[/tex]) is [tex]\( m = 2 \)[/tex].

### Step 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 slope of the original line. Therefore, the slope [tex]\( m_{\text{perp}} \)[/tex] of the perpendicular line is:
[tex]\[ m_{\text{perp}} = -\frac{1}{2} \][/tex]

### Step 3: Use the point-slope form to find the equation of the perpendicular line

The point-slope form of a line is given by:
[tex]\[ y - y_1 = m(x - x_1) \][/tex]
where [tex]\( (x_1, y_1) \)[/tex] is a point on the line, and [tex]\( m \)[/tex] is the slope of the line.

Using the point [tex]\( (4, 6) \)[/tex] and the slope [tex]\( -\frac{1}{2} \)[/tex], we plug these values into the point-slope form:
[tex]\[ y - 6 = -\frac{1}{2}(x - 4) \][/tex]

### Step 4: Simplify the equation

First, distribute the slope on the right-hand side:
[tex]\[ y - 6 = -\frac{1}{2}x + 2 \][/tex]

Next, add 6 to both sides to solve for [tex]\( y \)[/tex]:
[tex]\[ y = -\frac{1}{2}x + 2 + 6 \][/tex]
[tex]\[ y = -\frac{1}{2}x + 8 \][/tex]

### Step 5: Match the equation with the given options

The equation [tex]\( y = -\frac{1}{2}x + 8 \)[/tex] corresponds to option A.

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