DIRECT PROPORTION

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➣ QUESTION:

If y is directly proportional to (x+2)(x+5) and y = 6 when x = 1, find y when x = 4.

➣ ANSWER:

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➣ SOLUTION:

The variation of numbers is directly proportional. So the equation is:

We know that y = 6 when x = 1, so we can plug in these values in the equation to solve for the nonzero constant k.

The nonzero constant is ⅓. The equation is now:

Hence, when x = 4, we have:

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