WEBVTT

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Here is the problem: negative 7x plus 20 equals negative 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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Subtract 20 from both sides.

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Divide both sides by negative 7.

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Now look at the graph of the left side minus the right side.

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It crosses zero exactly at the solutions we found.

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So the answer is x equals 3.

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