bonjour

( 4 x - 9 ) ( 10 + 2 x ) = ( 10 + 2 x ) ( 4 - 3 x )

( 4 x - 9 ) ( 10 + 2 x ) - (  10 + 2 x ) ( 4 - 3 x ) = 0

( 10 + 2 x ) ( 4 x - 9 - 4 + 3 x ) = 0

(  10 + 2 x ) ( 7 x - 13 )= 0

soit  2 x + 10 = 0 et x = - 10/2 = - 5

soit  7 x - 13 = 0 et x = 13/7

( 3 x + 1 ) ( 2 x  - 9 ) = ( 3 x + 1 ) ²

( 3 x + 1 ) ( 2 x - 9) - ( 3 x + 1 )²= 0

( 3 x + 1 ) ( 2 x - 9 - 3 x - 1 ) = 0

( 3 x + 1 ) ( - x - 10) = 0

même raisonnement

x =  - 1/3 ou - 10

( 4 x - 9 )² = 25

( 4 x - 9 ) - 25 = 0

( 4 x - 9 - 5 ) ( 4 x - 9 + 5) = 0

( 4 x - 14 ) ( 4 x - 4 ) = 0

x = 14/4 = 7/2

ou x = 4/4 = 1

( x - 8 )² - 18 = - 2

( x - 8 )² - 18 + 2 = 0

( x - 8 ) - 16 = 0

( x - 8 - 4 ) ( x - 8 + 4 )  = 0

(x - 12 ) ( x - 4 )  = 0

x = 12 ou 4