Algebrahard · Past Paper
Factorize a^4 + 4.
A(a^2+2a+2)(a^2-2a+2)
B(a^2+2)^2
C(a^2-2)^2
D(a+2)^2(a-2)^2
✓ Correct Answer: A — (a^2+2a+2)(a^2-2a+2)
Add and subtract 4a^2: (a^4 + 4a^2 + 4) - 4a^2 = (a^2+2)^2 - (2a)^2 = (a^2+2-2a)(a^2+2+2a).
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