College Algebra / Unit 2 Alg 093 short lesson, about 20 seconds
The Sum and Difference of Cubes
Captions available
The idea
The sum of cubes factors as a³ + b³ = (a + b)(a² − ab + b²); the difference mirrors it with the signs flipped.
In practice
x³ + 8 = (x + 2)(x² − 2x + 4); multiplying back, the middle products cancel in pairs.
Where people slip
The trinomial's middle sign opposes the binomial's.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
- Nothing. This is a starting point.
Unlocks
- Nothing yet depends on this.
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