（1）（3x-2y)^2=9x^2+(?)-(?)(2)(-3a^2-b)^2=(?)+b^2+(?)(3)(?+2c)^2=25t^2+4c^2+(?)(4)(?+1/2a)^2
问题描述：
（1）（3x-2y)^2=9x^2+(?)-(?)(2)(-3a^2-b)^2=(?)+b^2+(?)(3)(?+2c)^2=25t^2+4c^2+(?)(4)(?+1/2a)^2
(4)(?+1/2a)^2=?+1/4a^2-ab
答
（1）（3x-2y)^2=9x^2+(?)-(?)（3x-2y）^2=9x^2+4y^2-12xy(2)(-3a^2-b)^2=(?)+b^2+(?)(-3a^2-b)^2=9a^4+b^2+6a^2b(3)(?+2c)^2=25t^2+4c^2+(?)(5t+2c)^2=25t^2+4c^2+20tc(4)(?+1/2a)^2=?+1/4a^2-ab(-b+1/2a)^2=b^2+1/...