Question
How would you find the zeroes for this?
x^2+3x-9
x^2+3x-9
Answers
drwls
The zeroes of the function or "roots" are not integers or fractions in this case. Use the quadratic equation.
The roots are
[-3 +/- sqrt (9+36)]/2 = -4.854 and 1.854
The roots are
[-3 +/- sqrt (9+36)]/2 = -4.854 and 1.854
Lena
can't you partial factor
x^2+3x+9
x^2+3x=0
x(x+3)=0
x= 0 or x=-3
what am I doing wrong?
x^2+3x+9
x^2+3x=0
x(x+3)=0
x= 0 or x=-3
what am I doing wrong?
drwls
The equation you wrote was x^2+3x-9, not x^2+3x+9. Neither factors in the manner you have shown. You can't just throw out the 9, as you have done.
Lena
Then when is partial factoring used?