Asked by peter
completing the square
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
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
Answers
MathMate
3x²+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
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