Solving Equations (Leaving Cert Mathematics): Flashcards

Complex roots

Quadratic formula

$az^2+bz+c=0$

$z=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

Negative number under square root causes error

Negative discriminant ($b^2-4ac<0$)

Coefficients

$2i$

Roots involving $i$ when discriminant is negative

$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

$ax^2+bx+c=0$

$b^2-4ac$

Discriminant is negative: $b^2-4ac<0$

$-1$

Imaginary unit where $i^2=-1$

$a$, $b$, $c$

Show full working using quadratic formula

Real part $\pm$ imaginary part $i$