\(B=(2a-3)(2a+3)-a(3+4a)+3a+1\\=4a^2-9-3a-4a^2+3a+1\\=(4a^2-4a^2)+(3a-3a)+1-9\\=-8\\\to đpcm\\C=(4-c)(4-c)+(2-c)c+6c+2002\\=16-8c+c^2+2c-c^2+6c+2002\\=(c^2-c^2)+(2c+6c-8c)+16+2002\\=2018\\\to đpcm\\D=(m^2-2m+4)(m+2)-m^3+(m+3)(m-3)-m^2-18\\=m^3+8-m^3+m^2-9-m^2-18\\=(m^3-m^3)+(m^2-m^2)+8-9-18\\=-19\\\to đpcm\)