For the equation x2+x-6=0, the roots are
One and only one real number
Real with sum one
Real with sum zero
Real with product zero
When x<0, x=-x
∴Equation is x2-x-6=0⇒x=-2,3
∵x<0, ∴x=-2 is the solution.
When x≥0, x=x
∴Equation is x2+x-6=0⇒x=2, -3
∵x≥0, ∴x=2 is the solution.
Hence x=2, -2 are the solutions and their sum is zero.