y = 10x
4x= y
a varies directly as b and a = 12 when b = 4. What is the constant of variation?
y = 3x y = 3*19 = 57
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If P varies directly with the square of Q then the equation would be in the form of P = kQ2, where k is the constant of variation so the new equation would be: P = 6Q2, so when Q = 12 we have P=6*122, or P = 864
Find an equation of variation where y varies directly as x. One pair of values is y = 80 when x = 40
4x= y
a varies directly as b and a = 12 when b = 4. What is the constant of variation?
40
57
y = -5
15
direct variation: y = kx y = kx k = y/x = 0.8/0.4 = 2
y = 3x y = 3*19 = 57
y = kx: 10 = 37k so k = 10/37 and y = 10x/37
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