factor this equation 4-49w^2
\(4-49w^2=\ \ \ \ | use\ fromula\ (a^2-b^2)=(a-b)(a+b)\\\\ 4-49w^2=(2^2-(7w)^2)=(2-7w)(2+7w)\\\\ after\ factorisation: \ 4-49w^2=(2-7w)(2+7w)\)
