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Math

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Find the equation of the straight line joining

a)(4, 4) and ( 2, 0)
b)(3, -1), (5, 4)

i also need to know how you went about solving this problem so i can understand.. many thanks

  • Math - ,

    take the generic straight line:

    y=mx + b.
    Put in the first point: (4,4)
    4=4m+b let this be the equation 1)
    put in the second point in the generic
    0=2m+b
    Now you have two equations, and two unknowns (m,b). Solve them. In this case subtract the second equation from the first, which yields
    4=2m or m=2
    This makes b=-4 check that.

  • Math - ,

    A slight variation of bobpursey's method for #2

    slope = (4+1)/(5-3) = 5/2

    let the equation be y = (5/2)x + b
    sub in the point (5,4)
    4 = 5/2(5) + b
    8 = 25 + 2b
    b = -17/2

    so y = (5/2)x - 17/2

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