bonjour
A = ( x + 2 ) ( x - 7 ) = x² - 7 x + 2 x - 14 = x² - 5 x - 14
b = ( 3 x - 5 )² = 9 x² - 30 x + 25
C = ( x + 2 )² + ( 2 x - 11 ) ( x + 2 )
= x² + 4 x + 4 + 2 x² + 4 x - 11 x - 22
= 3 x² - 3 x - 18
7 ( x - 2 ) + x ( x - 12 )
= 7 x - 14 + x² - 12 x
= x² - 5 x - 14