Réponse:
a)x²-8x +16=(x-4)²
b)16x²+56x+49=(4x +7)²
c)49x²-140x+100=(7x-10)²
d)100x²-40x+4=(10x-2)²
e)4x²-20x+25=(2x-5)²
f)25x²-80x+64=(5x-8)²
