In algebra, letters are used when numbers are not known. Algebraic terms, such as \(2s\) or \(8y\), leave the multiplication signs out. So rather than \(2 \times s\), write \(2s\), and rather than \(8 ...

To expand a bracket means to multiply each term in the bracket by the expression outside the bracket. For example, in the expression \(3(m + 7)\), multiply both \(m\) and 7 by 3, so: \(3(m + 7) = 3 ...

Eric Larson and Isabel Vogt have solved the interpolation problem — a centuries-old question about some of the most basic objects in geometry. Some credit goes to the chalkboard in their living room.