Find all zeros for f(x)=x(5x-2)(x^2+1)

Factoring x2+5x-1

The first term is, x2 its coefficient is 1 .
The middle term is, +5x its coefficient is 5 .
The last term, "the constant", is -1

Step-1 : Multiply the coefficient of the first term by the constant 1 • -1 = -1

Step-2 : Find two factors of -1 whose sum equals the coefficient of the middle term, which is 5 .

-1 + 1 = 0

Conclusion : Trinomial can not be factored

Final result :

x2 + 5x - 1
This is what did but I not sure it's right?!

1603 is the correct one.