7-20  㡣
⣺Enterȷϡ
>> m=sym('[x,x^2,x*2,1/x]')
m =
[   x, x^2, x*2, 1/x]
>> n=sym('[2*x,y,x,x^2]') 
n =
[ 2*x,   y,   x, x^2] 
>> m+n 
ans = 
[     3*x,   x^2+y,     3*x, 1/x+x^2]
>> m-n
ans = 
[      -x,   x^2-y,       x, 1/x-x^2] 
>>
