Question 191785
First note that 4 is the common factor of the two terms. So we need to factor it out.
{{{16-4x^2}}}
={{{4(4-x^2)}}}
={{{4(2^2-x^2)}}}
={{{4(2+x)(2-x)}}}   use the formula {{{a^2-b^2=(a+b)(a-b)}}}