如图,已知抛物线y=x2﹣2bx﹣3(b为常数,b<0).
—________your brother speak French?
—Yes, he has learnt it in Paris for three years.
已知样本容量为30,样本频数分布直方图中各小长方形的高的比依次是2:4:3:1,则第二小组的频数是( )
下列关系式中:①y=2x;②yx=5;③y=﹣7x;④y=5x+1;⑤y=x2﹣1;⑥y=1x2;⑦xy=11,y是x的反比例函数的共有( )