E=(2x+1)²-2(x-1)²+(1-x)(x+3)
E=4x²+4x+1-2(x²-2x+1)+x+3-x²-3x
E=4x²+4x+1-2x²+4x-2+x+3-x²-3x
E=x²(4-2-1)+x(4+4+1-3)+1-2+3
E=x²+6x+2
(a+b)²=a²+2ab+b²
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