The Quadratic Formula Flashcards

All 5 cards in this deck

State the quadratic formula.

For $ax^2+bx+c=0$, $x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

In the quadratic formula, what does the $\pm$ sign tell you?

There are two solutions — one using $+\sqrt{\ }$ and one using $-\sqrt{\ }$.

True or false? In the quadratic formula only the $\pm\sqrt{b^2-4ac}$ part is divided by $2a$.

False. The whole of $-b\pm\sqrt{b^2-4ac}$ is divided by $2a$.

True or false? For $5x^2-4x-3=0$, the values to substitute are $a=5$, $b=-4$, $c=-3$.

True. The minus signs belong with the coefficients.

How many solutions does a quadratic equation have if $b^2-4ac=0$?

One (repeated) solution.

e.g. $x^2-2x+1=0$ gives only $x=1$