Répondre :
(a-3).(x+4)-(5-x).(a-3)= (a-3)(x+4 - 5 +x) = (a-3)(2x-1)
5a.(a+2)²-3a².(a+2)= a(a+2)(5a+10- 3a) = a(a+2)(2a+10)
25a²-(2a-3b)²= (5a - 2a + 3b)(5a + 2a - 3b) = 3(a+b)(7a-3b)
a.(2x-y)+b(y-2x)= a.(2x-y)-b(2x-y)= (2x-y)(a-b)
12x²y²-18xy + 24x = 6x(2xy² - 3y + 4)
-9/4b²+3/2b-1/4= -(9/4b²-3/2b+1/4) = - (3/2b - 1/2)²
1 - x^8 = (1-x^4)(1+x^4) = 1-x²)(1+x²)(1+x^4) = (1-x)(1+x)(1+x²)(1+x^4)
5a.(a+2)²-3a².(a+2)= a(a+2)(5a+10- 3a) = a(a+2)(2a+10)
25a²-(2a-3b)²= (5a - 2a + 3b)(5a + 2a - 3b) = 3(a+b)(7a-3b)
a.(2x-y)+b(y-2x)= a.(2x-y)-b(2x-y)= (2x-y)(a-b)
12x²y²-18xy + 24x = 6x(2xy² - 3y + 4)
-9/4b²+3/2b-1/4= -(9/4b²-3/2b+1/4) = - (3/2b - 1/2)²
1 - x^8 = (1-x^4)(1+x^4) = 1-x²)(1+x²)(1+x^4) = (1-x)(1+x)(1+x²)(1+x^4)