1.已知关于x的方程x2+bx+a=0有一个根是a(a≠0),则a+b的值为( )
| A. | 2 | B. | -1 | C. | 0 | D. | 1 |
17.两根木条,一根长30cm,一根长16cm,将它们一端重合且放在同一直线上,此时,两根木条的中点之间的距离为( )
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| A. | 7cm | B. | 23cm | C. | 7cm或23cm | D. | 14cm或46cm |