Which number is the discriminant of a quadratic equation whose roots are real unequal and irrational.
0, -5, 7, 4, -9
The discriminant is the part under the square root in the quadratic equation.
Square root of a positive number gives you a real number, as apposed to a negative number giving an imaginary number. So you know the number is positive.
They are unequal, so it can't be zero since 0 and -0 are the same.
Finally, irrational numbers aren't whole numbers so any number whose square root is a whole number is also out (ie sqrt(4)=2).
So that only leaves 7.... hope that helps.
