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Split the Plus-Minus

Part of the Factoring & Quadratics section of Coddy's Algebra journey. Lesson 48 of 61.

After you work out the square root, one line holds both answers: x=−5±12x = \frac{-5\pm 1}{2}. The ± carries two equations in one line. The last step is to split it. The plus case is x=−5+12=−2x = \frac{-5+1}{2} = -2. The minus case is x=−5−12=−3x = \frac{-5-1}{2} = -3.

Splitting the ± is a step you do yourself, just like splitting a zero product into two equations. Write the two cases, then work out each one to a single number.

Write the plus case and the minus case on separate lines. Work out each line on its own, so the two sign choices never get mixed in one calculation.

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Challenge

Medium

Solve x2+9x+8=0x^{2}+9x+8 = 0 with the quadratic formula. Split the ± into two cases at the end.

Try it yourself

x2+9x+8=0x^{2}+9x+8 = 0

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