(x^2+11x+24)(x^2+14x+24)-4x^2=(x^2+12.5x+24-1.5x)(x^2+12.5x+24+1.5x)-4x^2=(x^2+12.5x+24)²-(1.5x)²-4x^2=(x^2+12.5x+24)²-2.25x²-4x^2=(x^2+12.5x+24)²-6.25x²=(x^2+12.5x+24)&#...大哥84x^2-271x+195 配方法怎样做84x^2-271x+195 =84(x^2-271x/84+195/84)=84[x^2-271x/84+(271/168)²+195/84-73441/28224]=84[x^2-271x/84+(271/168)²+65520/28224-73441/28224]=84[(x-271/168)²-7921/28224]=84[(x-271/168)²-(89/168)²]=84(x-271/168-89/168)(x-271/168+89/168)=84(x-360/168)(x-182/168)=84(x-15/7)(x-13/12)=(7x-15)(12x-13)