① 1-36b²
=(1+6b)(1-6b)
② 12x-3y²
=3(4x-y²)
③ 0.49p²-144
=(0.7p+12)(0.7p-12)
④ （2x＋y）²-（x＋2y）²
=(2x+y)²-(x+2y)²
=4x²+y²+4xy-x²-4xy-4y²
=3x²-3y²
=3(x²-y²)
=3(x+y)(x-y)