1) 14x+21y= ?
2) mx+my+6x+6y= ?
3) a²+12a+36= ?
4) b²+4a²-4ab= ?
5) 25x²-y²= ?
6) 16x²-4= ?

1. 14х+21у=7(2х+3у)
2. mx+my+6x+6y=m(x+y)+6(x+y)
3. a^2+12a+36=a^2+2a+6^2=(a+6)^2
4. b^2+4a^2-4ab=b^2-4ab+4a^2=(b-2a)^2
5. 25x^2-y^2=5^2×x^2=(5x)^2-y^2=(5x-y)(5x+y)
6. 16x^2-4=4(4x-1)=4(2x-1)(2x+1)