your friend says the sum of two linear expressions is always a linear expression. is your friend correct? explain.

the sum of two linear expressions is always a linear expression

Lets take an example of two linear expression

first expression : 2x + 5

Second expression : 3x + 1

2x + 5 + 3x+1 = 5x + 6

When we add like terms we add only the numbers, x remains the same

So when we add two linear expression the resultant is an linear expression