bonjour
factorisation :
a.
81x²-1
= 9²x²-1²
=(9x)²-1²
=( 9x-1)(9x+1)
b.
64x²-1
= 8²x²-1²
= (8x)²-1²
=(8x-1)(8x+1)
c.
4x²-49
= 2²x²-7²
= (2x)²-7²
= (2x-7)(2x+7)
résoudre des équations degré 1:
a.
(2x-5)(2x+17)=0
= 2x-5=0
= 2x+17=0
X1=5/2;X2= -17/2
b.
(5x-5)(8x+7)=0
= 5x-5=0
= 8x+7=0
X1 =1;X2= -7/8
voilà !
