Mathematics — first biennium · Lesson
Do not start by memorizing the formula. Expand the general product: the two mixed products have equal magnitude and opposite signs, so they cancel. What remains is the square of the first term minus the square of the second.
The mixed terms +ab and −ab disappear because their sum is zero.
In this lesson: Understand and apply (a+b)(a-b)=a²-b² by recognizing cancellation of the mixed products.
You can already assume: Multiplying polynomials.
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