题目已知四个多项式A=x2+1A=x^{2}+1A=x2+1,B=x+1B=x+1B=x+1,C=mx−1C=mx-1C=mx−1,D=nx+1D=nx+1D=nx+1,下列说法中正确的个数为（ ）①若A=B2A=B^{2}A=B2,则x=1x=1x=1；②若A−D=B+CA-D=B+CA−D=B+C,则x=m+n+1x=m+n+1x=m+n+1；③若xxx为正整数,且A−2B2\frac{{A-2}}{{{B^2}}}B2A−2为整数,则x=1x=1x=1；④若2B⋅D=2nx2−nx+22B\cdot D=2nx^{2}-nx+22B⋅D=2nx2−nx+2,则当x>12x \gt \frac{1}{2}x>21时,D<BD \lt BD<B.A.111个B.222个C.333个D.444个知识点：整式化简求值章节：数与式 / 整式
