bonjour
R = 9 x² - 4 + ( 3 x - 2 ) ( x - 3 )
R = 9 x² - 4 + 3 x² - 9 x - 2 x + 6
R = 12 x² - 11 x + 2
( 9 x² - 4 ) = ( 3 x - 2 ) ( 3 x + 2 )
R = ( 3 x - 2 ) ( 3 x + 2 + x - 3 )
R = ( 3 x - 2 ) ( 4 x - 1 )
BC² = AC² + AB²
BC² = ( 2 x + 5 )² + 4 x²
BC² = 4 x² + 20 x + 25 + 4 x²
BC² = 8 x² + 20 x + 25
