Which identity justifies (2+sqrt3)(2−sqrt3)=1(2+\\sqrt{3})(2-\\sqrt{3})=1(2+sqrt3)(2−sqrt3)=1?
a2−b2=(a+b)(a−b)a^2 - b^2 = (a+b)(a-b)a2−b2=(a+b)(a−b)
(a+b)2=a2+2ab+b2(a+b)^2 = a^2+2ab+b^2(a+b)2=a2+2ab+b2
a3−b3=(a−b)(a2+ab+b2)a^3-b^3=(a-b)(a^2+ab+b^2)a3−b3=(a−b)(a2+ab+b2)
(a−b)2=a2−2ab+b2(a-b)^2=a^2-2ab+b^2(a−b)2=a2−2ab+b2