what is inreducible quadratic factor?

Answer 1

I suspect you mean irreducible. It is quadratic expression of the form ax^2 + bx + c that cannot be factored into monomials (a'x + b')(c'x + d') with real constants. This happens if b^2 < 4 ac

See
http://www.sosmath.com/algebra/factor/fac04/fac04.html
for further information

Answer 2

I need help with simplify fraction