)或a=( )时,a的平方等于2a

1、
a^2 =2a
a^2-2a=0
a(a-2)=0
a=0 或a =2
2、
设为x
(x+x ) + (x-x ) + (x/x) = 11.2
2x +1 =11.2
x=10.2/2 = 5.1