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( x - 3 )² = x² - 6 x + 9
( 4 x + 5 )² = 16 x² + 40 x + 25
3 ( x² - 36 ) = 3 x² - 108
5 ( 9 - 2 x )² = 5 ( 81 - 36 x + 4 x² ) = 20 x² - 180 x + 405
A (x) = ( x - 1 )² + x² + ( x + 1 )²
A (x) = x² - 2 x + 1 + x² + x² + 2 x + 1
A (x) = 3 x² + 2
3 x² + 2 = 1 325
3 x² = 1 325 - 2
3 x² = 1 323
x² = 441
x = √441 = 21
20 ² + 21 ² + 22 ² = 1 325
