Solve with the quadratic formula

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Learn it For ax² + bx + c = 0, x = (−b ± √(b² − 4ac)) ÷ 2a. Work out the discriminant b² − 4ac first; if it's not a perfect square, give decimal answers rounded as asked.

Example: Solve x² + 4x − 1 = 0 to two decimal places.

a = 1, b = 4, c = −1. b² − 4ac = 16 + 4 = 20.
x = (−4 ± √20) ÷ 2.
x ≈ 0.24 or x ≈ −4.24.

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