已知x=2 是关于x的方程x2-4x+c=0的一个根,则c的值是( )。
4
在美国教育史上,富兰克林于()年在费城首先创办了文实学校。
(A) 条件(1)充分,但条件(2)不充分. (B) 条件(2)充分,但条件(1)不充分. (C) 条件(1)和(2)单独都不充分,但条件(1)和条件(2)联合起来充分. (D) 条件(1)充分,条件(2)也充分. (E) 条件(1)和条件(2)单独都不充分,条件(1)和条件(2)联合起来也不充分.
Automobile A is traveling at two-thirds the speed that Automobile B is traveling. How fast is Automobile A traveling (1) If both automobiles increased their speed by 10 miles per hour, Automobile A would be traveling at three-quarters the speed that Automobile B would be traveling. (2) If both automobiles decreased their speed by 10 miles per hour, Automobile A would be traveling at half the speed that Automobile B would be traveling.