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? asked in Science & MathematicsMathematics · 2 months ago

write the equation of the line passing through the points (-2,4) and (1,-5) in slope intercept form.?

2 Answers

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  • 2 months ago
    Favorite Answer

    slope-intercept format looks like this:

    y = mx + c

    where m and c are usually numbers, and where

    m is the slope = how fast y rises, when x goes up by 1,

    c is the y-intercept (the value of y, when x=0)

    In an ordered pair, the coordinates are given in the order of (x, y)

    for these points, x goes from -2 to + 1 (an increase of +3)

    while y goes from 4 to -5 (a "rise" of -9 -- in other words, a decrease)

    The slope is, therefore, -9/3 = -3

    Every time x goes up by 1, y goes DOWN by 3.

    m = -3

    So far, we have

    y = -3x + c

    To find the value of c, we simply pick one point

    say (x, y) = (-2, 4)

    We use these values in the equation, and solve for c

    y = -3x + c

    becomes

    4 = -3(-2) + c

    4 = 6 + c

    -2 = c

    We now have everything we need. We put it all together

    y = mx + c

    is now

    y = -3x - 2

    We check this with the other point (x, y) = (1, -5)

    -5 = -3(1) - 2

    -5 = -3 - 2

    TRUE

  • 2 months ago

    m = (4 - (-5))/(-2 - 1) = -3, so

    y = -3x + b, where b is found from

    (4) = -3(-2) + b => b = -2.

    Answer: y = -3x - 2.

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