Quadratic Functions

You need to know: 

The general formula of a quadratic is

$$y=ax^2+bx+c$$ where \{a, b, c,\} are constants and $$a \neq 0$$

Quadratic equations can be solved by:

(i) factorisation by D.O.T.S 'ac' method seeing it       

(ii) completing the square      $x^2\pm bx=(x\pm\frac{b}{2}$)$^2$-($\frac{b}{2}$)$^2$

(iii) using the quadratic formula$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

remember plotting $\neq$ sketching!

How to sketch and get method marks:

$a > 0$ then $\cup$ , $a \(b^2-4ac > 0$ there are 2 real different roots, $b^2-4ac=0$ there are 2 equal $R$ roots, $b^2-4ac \(x$-axis crossing $y$-axis crossing

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