x²-5√3x+18x（x-5√3）+18x3+5x2+7x+3 =(x³＋5x²＋4x)＋(3x＋3) =x(x²＋5x＋4)＋3(x＋1) =x(x＋1)(x＋4)＋3(x＋1)=(x＋1)(x²＋4x＋3) =(x＋1)(x＋1)(x＋3) =(x＋1)²(x＋3) ...