HELP! Quadratic Equations.

How do you find the zeros and the lines of symmetry for the graphs of the following functions:

- $\displaystyle f(x) = x^2 - 4x + 1$
- $\displaystyle g(x) = x^2 + 6x - 11$
- $\displaystyle h(x) = x^2 - 24$

I know how to get the zeros for 1 and 2, but not 3. Is for #1 x = 3.87, 0.31 and for #2 x=1.47, 7.47 ?

I don't get what the line of symmetry is at all...

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How do you find the minimum and maximum value of these functions:

- $\displaystyle f(x) = x^2 - 3x + 9$
- $\displaystyle g(x) = -x^2 + 8x +2$
- $\displaystyle h(x) = x^2 - 49$

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Thank you!