Question 359057
Use the FOIL Method,
{{{(x^2+16)(x^2-16)=x^2x^2-16x^2+16x^2-16(16)}}}
{{{(x^2+16)(x^2-16)=x^(2+2)-256}}}
{{{highlight((x^2+16)(x^2-16)=x^4-256)}}}