y=-2x²-3x+1配方
问题描述：
y=-2x²-3x+1配方
答
y=-2x²-3x+1
=-2（x²+3x/2-1/2)
=-2[x²+2*3/4*x+(3/4)²-(3/4)²-1/2]
=-2[(x+3/4)²-17/16]
=-2(x+3/4)²+17/8
答
y=-2x²-3x+1
=-2(x²-3x/2)+1
=-2[x²-3x/2+(3/4)²]+2×(3/4)²+1
=-2(x-3/4)²+17/8