把 y= -2x的平方+x+3帮我配方
问题描述：
把 y= -2x的平方+x+3帮我配方
越详细越好```````````我急着用```````````拜托`````````````要步骤````````````
答
y=-2x^2+x+3
=-2(x^2-x/2)+3
=-2(X^2-x/2+1/16)+3+1/16
=-2(x-1/4)^2+49/16