If y varies directly with x, and y = 5 when x = 8, how do you write the direct linear variation equation and what is the value of x when y = 15?

1 Answer
K-POUNZ
Feb 9, 2016

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Explanation:

first derive a formula from that expression

y=kx

in this case k its a constant so we will find a constant first inorder to derive a formular

substitute the variables with numbers been given

5=k(8) then make k subject of the formular

k=#5/8# then make a formular from the constant

y= #5/8#x

now this is your direct linear equation y= #5/8#x

then use that equetion inorder to find the x value

finding x value, substitute the formula with the value given in this case y=15

then

y= #5/8#x

15= 0.625x

#15/0.625#=x

24=x

therefore x =24

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