Bonjour
N°41
A = (4x-1)² + (x+2)² il s'agit de 2 identités remarquables
A = (16x² - 8x +1) + (x² +4x +4)
A = 16x² -8x +1 +x² +4x +4
A = 17x² -4x +5
B = (5t+4)² +(5t+4)(5t-4) Tu as là 2 identités remarquables
= (25t² +40t +16) + (25t² -16) (a+b)(a-b) = a²-b²
= 25t² +40t +16 +25t² -16
= 50t² +40t
N°42
A = (7x-1)² +(7x+1)²
= 49x² -14x+1 + 49x² +14x +1
= 98x² +2
B = (5a-4)(a+2) - (a+2)²
= 5a²+10a -4a -8 - ( a² +4a +4)
= 5a² +6a -8 -a² -4a -4
= 4a² +2a -12
