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Miles
Lv 5
Miles asked in Science & MathematicsMathematics · 9 years ago

y=kx and y=kxz question?

Could somebody show step by step how to solve the following two problems? Thanks!

Given that y varies inversely as x, write an inverse-variation equation when y=18 and x=3. Then using the inverse variation equation, find y when x=9.

and

Given that y varies jointly as x and z, write a joint-variation equation when y=2, x=(1/4), and z=(1/2). Then using the joint variation equation, find y when x=7 and z=(1/8)

1 Answer

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  • ?
    Lv 7
    9 years ago
    Favorite Answer

    y varies inversely as x --> y = K / x where K is a constant

    "Inversely" means out it into the denominator

    Use your knowns to solve for K, then do the 2nd part of the problem

    18 = K / 3 --> K = 3(10)= 54

    y = 54/ 9 --> y = 6

    y varies jointly as x and z --> y = Kxz where K is a constant

    "jointly" means the variables go into the numerator

    Use the knowns to solve for K then do the snd part of the problem

    2 = K(1/4)(1/2)

    2 = K/8 --> K = 16

    y = 16 (7)(1/8) --> y = 14

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