4xy+1-4x²-y²=1 - (4x²+y²-4xy)= 1 ² - (2x-y)²=(1+2x-y)(1-2x+y)8x³+4x²-2x-1=(8x³+4x²)- (2x+1)=4x²(2x+1) - (2x+1)= (4x²-1)(2x+1)=(2x+1)² (...