math question - factoring
anybody know how to factor this?
3x^2 + 3x - 2 =0
thanks
There is not a "nice" solution...
... however, factorization IS possible.
All right, as english is not my prime language I can't talk well in english about maths, so try to follow me on this.
First of all, to see that the factorization IS possible, lets look at the graph of the function. It's minimal value is for x=-(1/2) and f(x):=3x^2 + 3x - 2
=> f( -(1/2) ) < 0. As a coefficient next to the "biggest" power is positive (3*x^2) that means that function grows when going to the left and right from the point x=-(1/2). Which means it intersects with the X at two points.
Now if we took a standard formula for solving equations of form:
a*x^2 + b*x + c = 0
which (formula) looks like:
x1 = ( -b + square root( b^2 - 4*a*c ) ) / 2*a
x2 = ( -b - square root( b^2 - 4*a*c ) ) / 2*a
and applied it to our polynom f(x)
we would get:
x1 = ( -3 + square root( 33 ) ) / 6
and
x2 = ( -3 - square root( 33 ) ) / 6
Now that means that f(x) = ( x - x1 ) * ( x - x2 ) * 3 ( 3 comes because of the coefficient next to the "biggest" power (3*x^2) )
End result:
3*x^2 + 3x - 2 = ( x + ( 3 - sqrt( 33 ) ) / 6 )*( x + ( 3 + sqrt( 33 ) ) / 6 )*3
= ( 6x + 3 + sqrt( 33 ) ) * ( 6x + 3 - sqrt( 33 ) ) / 12 = 0
As I said, not nice at all, but its right.
Kresho