# quadratic formula

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• Jun 2nd 2010, 02:23 PM
kelsikels
quadratic formula
3x(x-3)= -4

Help!
Thanks
• Jun 2nd 2010, 02:25 PM
pickslides
$\displaystyle 3x(x-3)= -4$

$\displaystyle 3x^2-9x= -4$

$\displaystyle 3x^2-9x+4= 0$

$\displaystyle a=3,b=-9,c=4$

Was that o.k?
• Jun 2nd 2010, 02:26 PM
Plato
Quote:

Originally Posted by kelsikels
3x(x-3)= -4

$\displaystyle 3x^2-9x+4=0???????$
• Jun 2nd 2010, 02:31 PM
kelsikels
what about the second part?
• Jun 2nd 2010, 02:35 PM
Plato
Quote:

Originally Posted by kelsikels
what about the second part?

What second part?
Do you mean the complete solution?
Oh no! That is your job!
• Jun 2nd 2010, 02:38 PM
e^(i*pi)
Quote:

Originally Posted by kelsikels
what about the second part?

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

Pickslides has given you values for a, b and c
• Jun 2nd 2010, 02:40 PM
pickslides
Quote:

Originally Posted by pickslides

$\displaystyle a=3,b=-9,c=4$

Substitute these values into

$\displaystyle x = \frac{-b\pm\sqrt{b^2-4ac}}{2a}$
• Jun 2nd 2010, 03:01 PM
bigwave
here's a graph of $\displaystyle 3x^2-9x+4= 0$ if it is of any interest
the x intercepts are not as obvious as they look.
as mentioned already the quadradic equation will give the intercepts

http://www2.wolframalpha.com/Calcula...15&w=300&h=186