y=x²-4x+1=(x²-4x)+1=(x²-4x+4-4)+1=(x-2)²-4+1=(x-2)²-3开口向上,(2,-3),直线x=2y=-x²+2x+3=-(x²-2x)+3=-(x²-2x+1-1)+3=(x-1)²+2开口向下,(1,2),直线x=1y=3x...
y=x²-4x+1=(x²-4x)+1=(x²-4x+4-4)+1=(x-2)²-4+1=(x-2)²-3开口向上,(2,-3),直线x=2y=-x²+2x+3=-(x²-2x)+3=-(x²-2x+1-1)+3=(x-1)²+2开口向下,(1,2),直线x=1y=3x...