Question

写出下列二次函数表达式.1,y=x^22,y=2x^2+43,y=-2x^2-44,y=-2x^2+6x-1对称轴表达式

Answer 1

(1) y=x^2=(x-0)^2=x^2 对称轴：x=0

(2) y=2x^2+4=2(x-0)^2+4=2x^2+4 对称轴：x=0

(3) y=-2x^2-4=-2(x-0)^2-4=-2x^2-4 对称轴：x=0

(4) y=-2x^2+6x-1=-2(x^2-3x+9/4)+2*(9/4)-1

=-2(x-3/2)^2+7/2 对称轴：x=3/2