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The straight line L has equation 4x + y = 7 Find an equation of the straight line perpendicular to L that passes through (-8, 3).​

User Gbtimmon
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1 Answer

1 vote

Answer:

y = (1/4)x + 5

Explanation:

Lets rearrange the given equation into slope - intercept format of y = mx + b, where m is the slope and b is the y-intercept (the value of y when x is zero).

Line L: 4x + y = 7

y = -4x + 7

We find that the slope of line L, m, is -4.

A line perpendicular to L with have a slope that is the negative inverse of the slope of L. The negative inverse of -4 would be (1/4).

The new line, which we'll call P, will have the form of:

y = (1/4)x + b

Any line with a slope of (1/4) will be perpendicular to L.

But we want a line that also goes through point (-8,3). To make that happen, a value of b must be chosen to shift the line to (-8,3). The value of b that will do that can be calculated by entering that point in the equation y = (1/4)x + b:

y = (1/4)x + b

3 = (1/4)(-8) + b for (-8,3)

3 = -2 + b

b = 5

The line perpendicular to L and goes through (-8,3) is:

y = (1/4)x + 5

See the attached graph.

The straight line L has equation 4x + y = 7 Find an equation of the straight line-example-1
User Jkaram
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