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July 30, 2014

July 30, 2014

Posted by **peter** on Sunday, November 7, 2010 at 6:51am.

3x^2 +15 -33 =0

a=3

b=15

c=-33

-15+or- sqrt225-4*3*-33/2*3

-15+or-sqrt225+396/6

is this right because don't you have to subtract not add the 396

please help. thanks

- math -
**MathMate**, Sunday, November 7, 2010 at 7:15am3x²+15x-33

a=3, so

=3(x²+5x-11)

=3[(x+2.5)²-11-2.5²]

=3[(x+2.5)²-(√(17.25))²]

=3(x+2.5+√(17.25))(x+2.5-√(17.25)))

So

x=-2.5±√(17.25)

which you can also express integers as follows:

x=[-5±√(69)]/2

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