49(x+y)²-9(x-y)²
=(7x+7y+3x-3y)(7x+7y-3x+3y)
=(10x+4y)(4x+10y)
=4(5x+2y)(2x+5y)
(x²-5)²+8(x²-5)+16
=(x²-5+4)²
=(x²-1)²
=(x-1)²(x+1)²
49(x+y)²-9(x-y)²
=(7x+7y+3x-3y)(7x+7y-3x+3y)
=(10x+4y)(4x+10y)
=4(5x+2y)(2x+5y)
(x²-5)²+8(x²-5)+16
=(x²-5+4)²
=(x²-1)²
=(x-1)²(x+1)²