Inequality Graphing Problem: -1 <= x < 18 or x < 25

[tvanhooz]

So, my daughter came home with the following that she contends is correct, yet the teacher says it is not.

Graph:

-1<=x<18 OR x<25

We believe that with the OR, either has to be satisfied to be include in the resulting set.

We come up with: x<25 as the answer or (-infinity, 25) in interval notation.

The teacher says the result should be: (-infinity, 18) U (18,25). She is omitting 18; however, we think it should be part of result.

Thoughts? Thanks!

 

[pka]

So, my daughter came home with the following that she contends is correct, yet the teacher says it is not.

Graph: -1<=x<18 OR x<25

As written that is \(\displaystyle \Large [-1,18)\cup (-\infty,25)=(-\infty,25)\)

 

[tvanhooz]

As written that is \(\displaystyle \Large [-1,18)\cup (-\infty,25)=(-\infty,25)\)

Yep...that's what we got too. Now we just have to get the teacher to agree ; )

 

[Harry_the_cat]

So, my daughter came home with the following that she contends is correct, yet the teacher says it is not.

Graph:

-1<=x<18 OR x<25

We believe that with the OR, either has to be satisfied to be include in the resulting set.

We come up with: x<25 as the answer or (-infinity, 25) in interval notation.

The teacher says the result should be: (-infinity, 18) U (18,25). She is omitting 18; however, we think it should be part of result.

Thoughts? Thanks!

18 should be included. Why wouldn't it be? Did the teacher explain her answer?