Question

Is ( square root 12 -4)(4+square root 12) rational or irrational

Answer 1

Remember
(a-b)(a+b)=a²-b²

we can rewrite what we were given into
$( \sqrt{12}-4)( \sqrt{12}+4)=( \sqrt{12})^2-(4)^2=12-16=-4$
definitely rational