ShmoopTube

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And here is your shmoop de jour...

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What is a root of this equation? y2 - y = 4

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And here are the potential answers...

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OK so what is this question asking?

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Sneaky quadratic equation question. We need to pull the root numbers and plug them in

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and see what we get. Remember the quadratic equation? Our old buddy,

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old pal? When an equation is in the form ax squared

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plus bx plus c equals 0... ...the solution can be negative b plus or

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minus radical, b-squared minus 4ac all over 2a.

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That's the quadratic equation formula.

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That's a mouthful. Let's change the equation to y squared minus y minus

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4 equals 0... so it looks like ax squared plus bx plus c equals 0.

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We can see that a is 1, b is negative 1, and c is negative 4.

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When we start pluggin', we get that 1 plus or minus the square root of 1 minus 4 times

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1 times negative 4 all over 2... ...gives us 1 plus or minus the square root

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of 17 over 2. So now we have one solution, or root, of the equation.

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Looks like D.

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