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Write the equation of the line that passes through the points (7, –4) and (–1, 3), first in point-slope form, and then in slope-intercept form.

User Jammycakes
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1 Answer

15 votes
15 votes

Answer:

  • y +4 = -7/8(x -7)
  • y = -7/8x +17/8

Explanation:

Given two points, the equation for the line can be found by starting with determining the slope. Then the point-slope form can be used to find the equation. That form can be rearranged to give the slope-intercept form (or any other form you may desire.)

The slope formula is ...

m = (y2 -y1)/(x2 -x1)

m = (3 -(-4))/(-1 -7) = 7/-8 = -7/8

Then the point-slope form using the first point is ...

y -k = m(x -h) . . . . line with slope m through point (h, k)

y +4 = -7/8(x -7) . . . . . line with slope -7/8 through (7, -4)

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Eliminating parentheses, and subtracting 4 gives the slope-intercept equation:

y +4 = -7/8x +49/8 . . . eliminate parentheses

y = -7/8x +17/8 . . . . . subtract 4; slope-intercept equation

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The attached graph shows both forms of the equation draw the same line.

Write the equation of the line that passes through the points (7, –4) and (–1, 3), first-example-1
User Caffaddt
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3.2k points