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Completing the square, with actual squares
A seven-scene guided mini-lesson: watch x² + 8x literally become (x + 4)² − 16. ▶ Play all runs it as a lesson; Next / Back and ← → keys step through by hand.
our pieces
x
²
+
8
x
=
x
²
+
4
x
+
4
x
the big square
(
x
+ 4)²
=
x
²
+
4
x
+
4
x
+
16
so
x
²
+
8
x
=
(
x
+ 4)²
− 16
pay the corner back
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