(h5*x5+h4*x4+h3*x3+h2*x2+h1*x + h0) * (k5*x5+k4*x4+k3*x3+k2*x2+k1*x + k0)
Click [X].  Tke result is   p10*x10 + ... + p0

h5 h4 h3 h2 h1 h0

k5 k4 k3 k2 k1 k0


 p10  p9  p8  p7  p6  p5
p4  p3  p2  p1  p0

If you have to put a coefficient using some function symbol (for example 1/5, √2), put it in a numerical form (0.2, 1.414213562373095), for example using this

division   →   wolframalpha                                           then click [Show details]