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Find the equation of the line going through the point (-2,7) and perpendicular to 2x + y = 8.

A. 2x - y = 11
B. 2x - y = -11
C. 2x + y = 11
D. 2x + y = -11

User Ketly
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1 Answer

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Final answer:

To find the equation of the line perpendicular to 2x + y = 8, we calculate the negative reciprocal of the original line's slope (-2), which is 1/2. Then, using the point (-2,7), we find the y-intercept to be 8, leading to the equation 2x - y = -11 (Option B).

Step-by-step explanation:

To find the equation of a line that is perpendicular to a given line, you must first understand that perpendicular lines have slopes that are negative reciprocals of each other.

The given equation, 2x + y = 8, can be rewritten in slope-intercept form (y = mx + b) to find its slope. After rearrangement, we get y = -2x + 8, which tells us the slope (m) of the line is -2.

The slope of the line that is perpendicular to this will be the negative reciprocal of -2, which is 1/2. Therefore, our new line has a slope of 1/2 and goes through the point (-2,7). Using the slope-intercept form y = mx + b, and replacing m with 1/2 and inserting the point's coordinates to solve for b, we get:

7 = (1/2)(-2) + b

7 = -1 + b

b = 8

The equation of the line in slope-intercept form is y = (1/2)x + 8. To convert this to standard form, multiply the entire equation by 2 to eliminate the fraction:

2y = x + 16

Rearrange to get the standard form:

x - 2y = -16

Therefore, the correct answer is 2x - y = -11 (B), which after distributing 2 into the equation becomes 2x - (2*7) = -16, which then simplifies to 2x - 14 = -16, and adding 14 to both sides results in 2x = -2, and finally, dividing by 2 we get x = -1.

User Todd Motto
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