Question

Consider the interval [0, infinite symbol) . For each numerical value. Is it interval or not.

Answer 1

Since the given interval is

$\lbrack0,\infty)$

Then any number starting from zero to infinty belongs to it

The interval has zero and all positive real numbers

1) The given number is

$-4.2\times10^5$

Since the number is negative, then it does not belong to the given interval

$-4.2\times10^5\notin\lbrack0,\infty)$

2) The given number is

$10^{-3}$

Reciprocal it to change the sign of the power from negative to positive

$10^{-3}=\frac{1}{10^3}=\frac{1}{1000}$

Since the number is positive, then it belongs to the given interval

$10^{-3}\in\lbrack0,\infty)$

3) The given number is

$\lvert-8.5\rvert$

Since the absolute neglect the sign of the number, then

$\lvert-8.5\rvert=8.5$

Then the number is positive, so it belongs to the given interval

$\lvert-8.5\rvert\in\lbrack0,\infty)$