College Algebra / Unit 2 Alg 091 short lesson, about 20 seconds
The Sum of Squares
Captions available
The idea
A sum of squares does not factor over the real numbers: no product of real-coefficient binomials multiplies back to a² + b².
In practice
x² + 9 stays whole. Every candidate pair fails the multiply-back check — and for every real x, the value sits at 9 or above, never crossing zero.
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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