factoriser :   ( les x sont des x pas des fois) t²+81+18t 4x²-4xy+y² x²-16 1-y² 100x²-9 100+60x+9x²

t²+81+18t
=t²+2*9*t+9²
=(t+9)²

4x²-4xy+y²
=(2x)²-2*2x*y+y²
=(2x-y)²

1-y²
=1²-y²
=(1-y)*(1+y)

100x²-9
=(10x)²-3²
=(10x+3)*(10x-3)

100+60x+9x²
=10²+2*10*3x+(3x)²
=(10+3x)²