WEBVTT

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Here is the problem: x/(x plus 4) plus 9/(x minus 3) equals 1.

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A linear equation in x: isolate x using inverse operations.

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Start with the equation.

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Multiply both sides by x ^ 2 + x minus 12 to clear the fractions. This is only valid where x ^ 2 plus x minus 12 not equal to 0, so any value that makes it zero is excluded at the end.

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Isolate x.

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So the answer is x equals negative 48 over 5 approximately negative 9.6.

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Doing the same operation to both sides keeps the equation balanced. Undoing addition, then multiplication, leaves x alone.

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x equals negative 9.6: left side equals 1, right side equals 1, which checks out.