—Thanks a lot.
A:careful enough
B:enough careful
C:carefully enough
D:enough carefully
x-0.6=1
x=____
计算:
(1)若xm•x2m=2,求x9m的值;
(2)已知3×92m×27m=315,求m的值.
如图,在四棱锥P﹣ABCD中,PA⊥底面ABCD,底面ABCD是梯形,其中AD∥BC,BA⊥AD,AC与BD交于点O,M是AB边上的点,已知PA=AD=4,AB=3,BC=2.求证:BC⊥PM.