In a polynomial equation, the number of zeros its determined by the máximum exponent possible, in the equation.
So then, in this equation
first develope parenthesis, to eliminate it
then x (x^3 + 1) becomes x^4 + x
now add the other 2 terms to get
x^4 + x + 6x^2 -8x
then this equation should have 4 zeros
2nd part)
End behavior , how do you know
its the graph near x axis
First , it have a zero at x= 0
the second zero is at x= 1
it grows to infinity when x goes to infiniy
and grows to infinity when x goes to -infinity.