Here’s an example of a polynomial expression that has more complicated expressions we’ll need to substitute for a and b. We’ll set it up to mirror the structure of the perfect cube identity.
In this expression, a is represented by
and b is represented by
.
As we substitute
for a and
for b in the identity, we need to be careful to substitute exactly. For example, we don’t want to confuse the coefficient or the exponent in the b-term for exponents in the identity.
Next, simplify using the properties of exponents and multiplication to get the simplified expanded form. Look closely: this form mirrors the perfect trinomial identity with its own values for a and b.