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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
by
2.8k points

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

_____

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
by
3.2k points
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