Réponse :
Explications étape par étape
a)
9x²-42x + 49
a²- 2ab + b²= (a-b)²
(3x)²-2*7*3x + (7)²
(3x)²-42x+(7)²
= ( 3x - 7)²
b)
4x²-9
a²-b²=(a-b)(a+b)
(2x)²-(3)²
= (2x-3)(2x+3)
c)
25x²+30x+9
a²+2ab+b²= (a+b)²
25x²+30x+9
= (5x)²+ 2*5x*3 + (3)²
= (5x+3)²
d)
(5x+1)(3-2x)- (5x+1)(2x+1)
= (5x+1) ( (3-2x) - (2x+1))
= (5x+1) ( 3 - 2x -2x -1)
= (5x+1)( - 4x +2)
e)
(x+1)(2x-1)-(2x-1)*1
= (2x-1) ( x+1-1)
= (2x-1)x
f)
(2x-1)²* + (2x-1)(3x+1)
= (2x-1)(2x-1)+(2x-1)(3x+1)
= (2x-1) ((2x-1)+(3x+1))
= (2x-1) (2x-1+3x+1)
= (2x-1) (5x)
= 5x(2x-1)
