Quadratic Equations
A quadratic equation is any expression of the form:
ax2 + bx + c = 0, a ≠ 0.
Solving Quadratic Equations
To solve quadratic equations use the following formula:
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If a<0, multiply two members by (−1).
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Incomplete Quadratic Equations
A quadratic equation is incomplete if any of its coefficients: b or c, or both, are zero.
Solving Incomplete Quadratic Equations
ax2 = 0
The solution is x = 0.
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ax2 + bx = 0
Remove the common factor, x:
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The 1st factor equals 0.
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A solution is always x = 0.
The other solution was obtained by solving the linear equation resulting from equating the 2nd factor to zero.
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ax2 + c = 0

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