algebra

the value of y varies directly with x, and y= -14 when x = 1/2. find y when x = -1.

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asked by genny
  1. two ways to do this:

    1.

    "y varies directly with x " y = kx , where k is a constant
    when x = 1/2, y = -14
    -14= (1/2)k
    k = -28
    so y = -28x
    if x = -1
    y = -28(-1) = 28

    2. Just use a ratio:
    (1/2) / -14 = -1/y
    1/2)y = 14
    y = 28

    notice the actual "calculation " is the same

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    posted by Reiny

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