Question 943119
Integer coefficients  means complex roots come in complex conjugate pairs. 
So,
{{{y=a(x-2i)(x+2i)(x-(4-i))(x-(4+i))}}}
{{{y=a(x^2+4)(x^2-8x+17)}}}
{{{y=a(x^4-8x^3+21x^2-32x+68)}}}