$解：?(1)?將點?A(-2，??3)?代入?y=ax^2?可得?3=a×(-2)^2，?解得?a=\frac 34?$
$∴?y=\frac 34x^2?$
$當(dāng)?x=2?時，?y=\frac 34×2^2=3，?則函數(shù)圖像經(jīng)過點?A'(2，??3)?$
$當(dāng)?x=-1?時，?y=\frac 34×(-1)^2=\frac 34，?則函數(shù)圖像不經(jīng)過點?B(-1，??-2)?$
$?(2)?由對稱性可得，當(dāng)?x=2?或?-2?時，?y=3?$
$觀察該圖像可得，當(dāng)?x_c\lt -2?或?x_c\gt 2?時，?y_c\gt 3；?$
$當(dāng)?-2\lt x_c\lt 2?時，?y_c\lt 3 ?$
