Answer:
x⁴ - 256
Step-by-step explanation:
[tex]\bold{METHOD\ 1:}\\\\(x^2+16)(x^2-16)\qquad\text{use}\ a^2-b^2=(a-b)(a+b)\\\\=(x^2)^2-16^2\qquad\text{use}\ (a^n)^m=a^{nm}\\\\=x^{(2)(2)}-256\\\\=x^4-256[/tex]
[tex]\bold{METHOD\ 2:}\\\\(x^2+16)(x^2-16)\qquad\text{use FOIL:}\ (a+b)(c+d)=ac+ad+bc+bd\\\\=(x^2)(x^2)+(x^2)(-16)+(16)(x^2)+(16)(-16)\qquad\text{use}\ a^n\cdot a^m=a^{n+m}\\\\=x^{2+2}-16x^2+16x^2-256\qquad\text{cancel}\ 16x^2\\\\=x^4-256[/tex]
