Answer:
1. always
2. sometimes
Step-by-step explanation:
Two lines are coplanar if they lie in the same plane or in parallel planes. There is ALWAYS a plane which contains two parallel lines (see first attached image for details).
Two lines that lie in parallel planes are sometimes parallel. For example, see at second image. Planes and
are parallel. Consider pair of lines
and
- they are parallel, but if you consider the pair of lines
and
, you can see they are not parallel.
To add the variables, add the coefficients with same variable. The expression which is equivalent to given expression is . The option 2 is the correct option.
Equivalent expression are the expression whose result is equal to the original expression, but the way of representation is different.
Given information-
The expression given in the problem is,
Let the resultant expression of the above expression is . thus,
To add the algebraic terms open the brackets first,
Separate the same variable terms,
To add the variables, add the coefficients with same variable. Thus,
Hence, the expression which is equivalent to given expression is . The option 2 is the correct option.
Learn more about the equivalent expression here;
