14.已知ab=-5,a-b=6,则a2+b2=( )
| A. | 13 | B. | 19 | C. | 26 | D. | 37 |
13.在一次实验中,小明把一根弹簧的上端固定,在其下端悬挂物体,下面是测得的弹簧的长度y与所挂物体的质量x的一组对应值:
(1)上述反映了哪两个变量之间的关系?哪个是自变量?哪个是因变量?
(2)写出y与x之间的关系式,并求出当所挂重物为6kg时,弹簧的长度为多少?
0 286880 286888 286894 286898 286904 286906 286910 286916 286918 286924 286930 286934 286936 286940 286946 286948 286954 286958 286960 286964 286966 286970 286972 286974 286975 286976 286978 286979 286980 286982 286984 286988 286990 286994 286996 287000 287006 287008 287014 287018 287020 287024 287030 287036 287038 287044 287048 287050 287056 287060 287066 287074 366461
| 所挂重量x(kg) | 0 | 1 | 2 | 3 | 4 | 5 |
| 弹簧长度y(cm) | 18 | 20 | 22 | 24 | 26 | 28 |
(2)写出y与x之间的关系式,并求出当所挂重物为6kg时,弹簧的长度为多少?