Write $a^4 + 4$ as a product of two monic quadratics with integer coefficients.
Write $a^4 - 3a^2 + 9$ as a product of two monic quadratics with integer coefficients.
Let me show you how to do the first one; maybe you can follow the procedure to do the second one.
Problem: a4 + 4
Step 1 - complete the square; add and subtract that value: (a4 + 4a2 + 4) - 4a2
Step 2 - write as the difference of two squares: (a2 + 2)2 - (2a)2
Step 3 - factor: [ (a2 + 2) - (2a) ] [ (a2 + 2) + (2a) ]
Step 4 - remove the extra parentheses: (a2 + 2 - 2a) (a2 + 2 + 2a)
Step 5 - rewrite the terms (if you wish): (a2 - 2a + 2) (a2 + 2a + 2)
Can you do the second problem?