(x + 2) (x + 2) = x² + 2 x + 2 x + 4 = x² + 4 x + 4
( x - 2)² = x² - 4 x + 4
( x + 3)² = x² + 6 x + 9
( 2 x - 1) ( 2 x - 1) = 4 x² - 2 x - 2 x + 1 = 4 x² - 4 x + 1
x² + 8 x + 16 = ( x + 4)²
x² - 6 x + 9 = ( x - 3)²
( 2 x - 7) ( 2 x + 7) = 4 x² - 49
( 3 x + 8) ( 3 x - 8) = 9 x² - 64