Bonjour,
Ex. 1 :
a) E = (x-3)²-(x-1)(x-2)
= x²-6x+9-(x²-2x-x+2)
= x²-6x+9-x²+2x+x-2
= -3x+7
b) soit x=100 000
alors : 99 997 = x - 3
99 998 = x - 2
99 999 = x - 1
donc : 99 997² - 99 999 × 99 998
= (x - 3)² - (x - 1)(x - 2)
= -3x +7
= -3(100 000) + 7
= -300 000 + 7
= -299 993
2)
a) F = (4x+1)²-(4x+1)(7x-6)
= (4x+1)(4x+1)-(4x+1)(7x-6)
= (4x+1)[(4x+1)-(7x-6)]
= (4x+1)(-3x+7)
b) si x=-2
F = (4(-2)+1)(-3(-2)+7)
= (-8+1)(6+7)
= -91
