x^2-5x=14即:x^2-5x-14=0即:(x-7)(x+2)=0所以:x=7或x=-2当x=7时:(x-1)(2x-1)-(x+1)^2+1=(7-1)(14-1)-(7+1)^2+1=15当x=-2时:(x-1)(2x-1)-(x+1)^2+1=(-2-1)(-4-1)-(-2+1)^2+1=15
x²-5x=14原式=2x²-3x+1-x²-2x-1+1=x²-5x+1=14+1=15