The quadratic equation has two solutions if b^2 - 4ac > 0
Given the equation ax^4 + bx^2 + c=0
Substitute into the formula to have:
The equation becomes aP^2 + bP + c = 0
For us to have a unique solution, the discriminant b^2 - 4ac must be greater than zero. Hence the quadratic equation has two solutions if b^2 - 4ac > 0
learn more on discriminant here; brainly.com/question/1537997
Answer:
"It is not a solution because 9 is not greater than 9."
Step-by-step explanation:

If x is 9, then the inequality would be untrue because x must be GREATER than 9 not equal or greater.