—Oh, my God! It's really heavy. I can't imagine how big it is! Is it an adult elephant?
A:grams
B:kilograms
C:kilometres
如图,抛物线y=ax2+2ax+1与x轴仅有一个公共点A,经过点A的直线交该抛物线于点B,交y轴于点C,且点C是线段AB的中点.
已知方程x3+ax2+bx+c=0的三个实根可分别作为一椭圆,一双曲线.一抛物线的离心率,则a2+b2的取值范围是( )
日常生活中,下列做法合理的是( )