Question

If (x1, y1) and (x2, y2) satisfy xy = k, then x1y1 = x2y2. Find x or y as indicated.

(3, y) and (18, 6)

Answer 1

The first coordinate pair tells you \(3y=k\), and the second tells you \(18\times6=k\).

The second equations gives you \(k=108\).

Then \(3y=108~~\Rightarrow~~y=\dfrac{108}{3}=36\).