18.已知反比例函数y=$\frac{k-1}{x}$的图象经过点(-2,1).
(1)求k的值;
(2)判断下列各点否在这个图象上(-0.5,2),(4,-0.5),($\frac{1}{3}$,-6)
0 282577 282585 282591 282595 282601 282603 282607 282613 282615 282621 282627 282631 282633 282637 282643 282645 282651 282655 282657 282661 282663 282667 282669 282671 282672 282673 282675 282676 282677 282679 282681 282685 282687 282691 282693 282697 282703 282705 282711 282715 282717 282721 282727 282733 282735 282741 282745 282747 282753 282757 282763 282771 366461
(1)求k的值;
(2)判断下列各点否在这个图象上(-0.5,2),(4,-0.5),($\frac{1}{3}$,-6)