8 ( x + 5) = 8 * x + 8 *5 = 8 x + 40
3 x ( 2 x + 4) = 3 x * 2 x + 3 x * 4 = 6 x² + 12 x
( 2 x + 6 ) ( 2 x + 6 ) = 2 x * 2 x + 2 x * 6 + 6 * 2 x + 6 *6
= 4 x² + 12 x + 12 x + 36
= 4 x² + 24 x + 36
( 4 x - 5 ) x ( 4 x - 5 )
16 x² - 20 x - 20 x + 25
= 16 x² - 40 x + 25