Q. If x and y are in direct proportion and y is 14 when x is 2 , find y when x is 9 .Answer: y=
Write Equation: Write the equation that represents the direct variation between x and y. Since y varies directly with x, the equation can be written as y=kx, where k is the constant of variation.
Find Constant of Variation: Use the given values to find the constant of variation k. We know that y=14 when x=2. Substitute these values into the direct variation equation to find k. 14=k×2
Solve for k: Solve for k.Divide both sides of the equation by 2 to isolate k.214=2k×2k=7
Write Updated Equation: Write the direct variation equation using the value of k.Now that we know k=7, the direct variation equation is y=7x.
Find y for x=9: Find y when x=9.Substitute x=9 into the direct variation equation to find y.y=7×9y=63
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