1.设该抛物线的解晌仔析式为y=a(x-4)²+2把点(0,-6)代入得-6=16a+2a=-1/2所以y=-1/2(x-4)²+22.把y=0代入得0=-1/2(x-4)²+2x²-8x+16-4=0x²-8x+12=0(x-2)(x-6)=0x1=2 x2=63.因为隐谨橡a<0，函数图像开口向下，根据图像可知当2<灶旁x<6时，y>0
