1.858²-558²=(858+558)(858-558)=1416*300=4248002.202²+202×196+98²=(202+98)²=900003.x²-2xy+y²-9=(x-y)²-9=(x-y+3)(x-y-3)4.(x-4)(x+1)+3x=x²-3x-4+3x=x²-4=...