Question

solution=-1
Apply the quadratic formula.

Answer 1

the quadratic formula can only be applied to quadratic functions written in the form:
ax^2 + bx + c = o where a, b, c are all real numbers.

Answer 2

The quadratic equation whose solution is -1, if factored would be (x+1)(x+1)=0
Working that out would be:

x^2+2x+1=0