Develloper et réduire les expression : ( 7-3x)( 9x-3) ( -2 -3y )(4-8y) (4a+6)(-3-5a) (5z-7)(8z-2)

(7 - 3x) (9x - 3) = 
7 X 9x + 7 X (- 3) - 3x X 9x - 3x X (- 3) = 
63x - 21 - 27x² + 9x = 
- 27x² + 72x - 21

(- 2 - 3y) (4 - 8y) = 
- 2 X 4 - 2 X (- 8y) - 3y X 4 - 3y X (- 8y) = 
- 8 + 16y - 12y + 24y² = 
24y² + 4y - 8

(4a + 6) (- 3 - 5a) = 
4a X (- 3) + 4a X (- 5a) + 6 X (- 3) + 6 X (- 5a) = 
- 12a - 20a² - 18 - 30a = 
- 20a² - 42a - 18

(5z - 7) (8z - 2) = 
5z X 8z + 5z X (- 2) - 7 X 8z - 7 X (- 2) = 
40z² - 10z - 56z + 14 = 
40z² - 66z + 14

( 7-3x)( 9x-3)
=63x-27x²-21+9x
=-27x²+72x-21

( -2 -3y )(4-8y)
=-8-12y+24y²+16y
=24y²+4y-8

(4a+6)(-3-5a)
=-12a-18-20a²-30a
=-20a²-42a-18

(5z-7)(8z-2)
=40z²-56z-10z+14
=40z²-66z+14