计算:(1)(3x-5)²;(2)(-4a+1/2b)².
问题描述：
计算:(1)(3x-5)²;(2)(-4a+1/2b)².
答
(1)
(3x-5)²
=(3x)²-2*(3x)*5+5²
=9x²-30x+25
(2)
(-4a+1/2b)².
=(1/2b-4a)²
=b²/4 -4ab+16a²