Summary: A (A+B) = AA+AB = A+AB = A (I+B) = AI = AI-Complete Works AA = A (A the intersection of A and A is A) can be proved by set theory; It can be proved by Boolean algebra.

Elementary algebra starts with the simplest one-dimensional linear equation. On the one hand, elementary algebra further discusses binary and ternary linear equations, on the other hand, it studies equations that are larger than quadratic and can be reduced to quadratic. Along these two directions, algebra discusses the linear equations with any number of unknowns, also known as linear equations, and also studies the univariate equations with higher degrees.

This stage is called advanced algebra. Advanced algebra is a general term for the development of algebra to an advanced stage, including many branches. Higher algebra offered by universities now generally includes two parts: linear algebra and polynomial algebra.

The development content of higher algebra

In higher algebra, linear equations (also known as "linear equations") developed into linear algebra theory; Quadratic unary equation (also called "polynomial equation") developed into polynomial theory. The former is a branch of higher algebra, including vector space, linear transformation, type theory, invariant theory and tensor algebra, while the latter is a branch of higher algebra, which studies any degree equation with only one unknown number.