Sagot :
112/
a/ (3x+1)²
(3x+1)(3x+1)
9x²+3x+3x+1
9x²+6x+1
b/(7-x)²
(7-x)(7-x)
49-7x-7x+x²
x²-14x+49
c/(9-5x)(9+5x)
81+45x-45x-25x²
-25x²+81
112/
a/ (3x+1)²
(3x+1)(3x+1)
9x²+3x+3x+1
9x²+6x+1
b/(7-x)²
(7-x)(7-x)
49-7x-7x+x²
x²-14x+49
c/(9-5x)(9+5x)
81+45x-45x-25x²
-25x²+81