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1. The quadratic graph \( y = a(x - p)(x - q) \) crosses the \( x \)-axis at
\( (p,0) \) and \( (q,0) \).
The quadratic graph \( y = a(x - h)^2 + k \) has vertex \( (h,k) \) and
line of symmetry \( x = h \).
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2. You should be able to complete the square:
\[
x^2 + bx + c
= \left(x + \frac{b}{2}\right)^2 - \left(\frac{b}{2}\right)^2 + c.
\]
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3. You should be able to solve quadratic equations by factorizing,
completing the square, and using the quadratic formula.
If \( ax^2 + bx + c = 0 \), then
\[
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}.
\]
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4. You should be able to solve quadratic inequalities.
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5. You should be able to use the discriminant \( \Delta \) to determine the
number of roots of a quadratic equation, where
\( \Delta = b^2 - 4ac \).
If \( \Delta > 0 \), there are two distinct real roots;
if \( \Delta = 0 \), there are two equal real roots;
and
if \( \Delta < 0 \), there are no real roots.