A-SSE.A. Interpret the structure of expressions.
A-SSE.A.1. Interpret expressions that represent a quantity in terms of its context.
A-SSE.A.1.a. Interpret parts of an expression, such as terms, factors, and coefficients.
A-SSE.A.1.b. Interpret complicated expressions by viewing one or more of their parts as a single entity. For example, interpret $P(1+r)^n$ as the product of $P$ and a factor not depending on $P$.
A-SSE.A.2. Use the structure of an expression to identify ways to rewrite it. For example, see $x^4 - y^4$ as $(x^2)^2 - (y^2)^2$, thus recognizing it as a difference of squares that can be factored as $(x^2 - y^2)(x^2 + y^2)$.