## Calculus with Applications (10th Edition)

$4\leq x<10$
This is a half-open interval (one endpoint included, the other excluded). The left endpoint, 4 is included in the interval, while the right endpoint, 10, is not.. $($9.99, 9.9999, 9.9999999 etc. are in the interval, but 10 itself is not) So if x is a number in this interval, it will be between 4 and 10 , with the possibility of being 4 or greater and less than ten (but not equal to ten). . We can write this as $4\leq x<10$