Roberto’s teacher writes the following statement on the board: The cube of a number plus one more than the square of the number is equal to the opposite of the number. Show that the number is -1.
_________________________
This is x^3+x^2+1=-x in math terms, where x is the number. So x^3+x^2+x+1=0. We can write this: x^2(x+1)+(x+1)=(x^2+1)(x+1)=0. The only real solution is x+1=0, so x=-1. Hopefully that makes sense
