S = 7x^2....divide both sides by 7
1/7s (same as s/7) = x^2...now take sqrt of both sides
(+ - ) sqrt 1/7s = x
They show the decomposition of a multiplication expression into smaller parts
Intersection means elements both have. Both sets have -1 but they have nothing else in common so the intersection is {-1}
Union means combining the sets so {-1, 1, 2, 3, 7} Note that I only wrote 1 twice. No duplicates allowed!
