f(x)=x(x+3)(x+1)(x-4)f(x)=x(x+3)(x+ 1)(x−4)f, left parenthesis, x, right parenthesis, equals, x, left parenthesis, x, plus, 3, right parenthesis, left parenthesis, x, plus, 1, right parenthesis, left parenthesis, x, minus, 4, right parenthesis has zeros at x=-3x=−3x, equals, minus, 3, x=-1x=−1x, equals, minus, 1, x=0x=0x, equals, 0, and x=4x=4x, equals, 4. What is the sign of fff on the interval -1