【简答题】已知x 2 -4x+1=0,那么 x 2 x 4 -4 x 2 +1 的值是______.
【简答题】已知x=1,求 2x+4 x 2 -4x+4 ÷ x 3 +8 2x+4 ?( x 2 -4) 的值.
【判断题】日常生活中,我们把电源与用电设备之间脱离电器连接的现象称为断电。
【单选题】82 Which of the following are included in the Acquisition phase(s) of the project life cycle.
A.
concept and development
B.
development and planning
C.
execution and phase-out
D.
planning and implementation
【简答题】已知x 1 ,x 2 是方程x 2 -4x+2=0的两根,求:(1) 1 x 1 + 1 x 2 的值;(2)(x 1 -x 2 ) 2 的值.
【简答题】(1)已知:x+ 1 x =2,试求出 x 2 + 1 x 2 的值; (2)已知:x 2 -2x-1=0,你能求出 x 2 x 4 +1 的值吗?
【单选题】164 Which of the following are included in the Acquisition phase(s) of the project life cycle.
A.
concept and development
B.
development and planning
C.
execution and phase-out
D.
planning and implementation
【简答题】已知数据x 1 ,x 2 ,x 3 ,x 4 ,x 5 的平均数为a,则数据4x 1 ,4x 2 ,4x 3 ,4x 4 ,4x 5 的平均数为______;4x 1 -2,4x 2 -2,4x 3 -2,4x 4 -2,4x 5 -2的平均数为______.