```
cvx_begin;
variable a;
variable b;
minimize((a+1)*(b+2));
subject to
a>0;
b>0;
a*b-a-2*b-2==0;
cvx_end;
#########################
The error is:
错误使用 .* (line 262)
Disciplined convex programming error:
Invalid quadratic form(s): not a square.
出错 * (line 36)
z = feval( oper, x, y );
出错 Test_cvx2 (line 6)
minimize((a+1)*(b+2))
```

#########################

Do the math by hand: min((a+1)*(b+2))=25, when a==4,b==3

Please help me