Equations of lines. Find an equation of the line.?

Find an equation of the line having the given slope and containing the given point.

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

Now I understand that (y-y1)= m(x-x1) and I followed it through but its the solving for y when it comes to fractions that is giving me the hardest time. I think its throwing me off when I subtract or add using fractions. Any help would be greatly appreciated. Thanks in advance.

7 Answers

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  • 1 decade ago
    Favorite Answer

    (y-y1)= m(x-x1)

    Use the point (7, -2) as (x1, y1)

    The beauty about fractions is cross multiplication:

    (y-(-1))= 3/4 (x-7)

    (y+1) = 3/4 (x-7)

    Multiply both sides by 4, the denominator of the slope.

    4(y+1) = 3(x-7)

    4y + 4 = 3x - 21

    4y = 3x - 21 - 4

    4y = 3x - 25. This is the line you needed.

    In slope intercept form:

    y = 3x/4 - 25/4

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  • 1 decade ago

    Firstly, just write

    y = mx + b,

    Then, you know m, so

    y = (3/4)x + b

    Now, you know a point, so we can solve for b

    -1 = (3/4)*7 + b

    -1 = 21/4 + b

    b = -1 - 21/4 = -6.25 (use a calculator if you don't like fractions)

    So, now, we know m, and b, and we just write

    y = (3/4)x - 6.25

    Thus, that is the equation of your line.

    Hope this helps.

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  • 1 decade ago

    y+1=3/4(y-7)

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  • 3 years ago

    Slope intercept for is: y = mx + b considering which you have each and every of the values different than b you are able to fill in and resolve for b. y = mx + b -5 = (4/5)(0) + b -5 = 0 + b b = -5 So, y = (4/5)x - 5

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  • 1 decade ago

    (y + 1) = 3/4 (x- 7) multiply by 4

    4y + 4 = 3x - 21

    4y = 3x - 25

    y = 3/4 x - 25/4

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  • 1 decade ago

    A linear equation is as follows:

    y=mx+c

    y=3/4x-1

    is your equation

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  • Anonymous
    1 decade ago

    You have to revise about fraction !

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