bonjour
( 3 x + 1 ) ( 5 x - 4 )
= 15 x² - 12 x + 5 x - 4
= 1 5 x² - 7 x - 4
( - 2 a + 3 ) ( 10 - 4 a)
= - 20 a + 8 a² + 30 - 12 a
= 8 a² - 32 a + 30
( 5 x + 4 )²
= 25 x² + 40 x + 16
( - 3 b + 9)²
= - ( 3 b - 9 )²
= - ( 9 b² - 54 b + 81 )
5 y² +3 - ( 8 y + 3 ) ( 7 + y )
= 5 y² + 3 - ( 56 y + 8 y² + 21 + 3 y )
= 5 y² + 3 - 56 y - 8 y² - 21 - 3 y
= - 3 y² - 59 y - 18
