| by Kenneth Chase | 6 comments

## Identity property of 1 (second example) | Arithmetic properties | Pre-Algebra | Khan Academy

Evaluate 1x when x is equal to
negative 1, x is equal to 0, and x is equal to 1. So let’s do the scenario
x is equal to negative 1. Then 1x becomes 1 times x,
which is now negative 1. So it’s 1 times negative 1. Well, there’s a couple of
ways to think about it. 1 times anything is going
to be that anything. So 1 times negative 1 is going
to be equal to negative 1. Another way you could
have thought about it is you could’ve just looked
at the absolute value of both numbers. You’d say 1 times 1 is 1. They have different signs. So it’s going to be negative. It would have gotten you
the same answer either way. Now we have the scenario
where x is equal to 0. So 1 times x is going to be
the same thing as 1 times 0. We’ve substituted a 0 for x. Once again, 1 times anything is
going to become that anything. So this is going to become 0. Another way to think about
it is 0 times anything is going to become 0. So either one of those
ways of thinking about it would have gotten
you this answer. 1 times– actually,
we could even write 1 times x is equal to x. So really, when you
evaluate any of these at x is equal to negative 1, or
x is equal to 0, or x equals 1, it’s really just going
to equal that number because 1 times anything
is equal to that anything right over there. Just to make it clear, 0
times anything is equal to– and this x here is a variable
not a multiplication sign– 0 times anything is equal to 0. Just for good measure–
let’s try x is equal to 1. So this will give us 1 times
1, which you’ve probably learned a while ago. But 1 times anything is
equal to that number. So it’s equal to 1.

#### btkw

Jan 1, 2011, 12:44 pm Reply

WTF IS THIS?

#### Julio Caceres

Jan 1, 2011, 2:54 pm Reply

@btkw the basics

#### paulceltics

Apr 4, 2011, 2:53 am Reply

i like these short quick ones

#### Evi1M4chine

Jun 6, 2011, 5:18 am Reply

0 ∙ ∞ = 1
🙂

#### Evi1M4chine

Jun 6, 2011, 5:19 am Reply

And, no I don’t care what you think, unless you came up with it 100% yourself. Which you may think you do, but you extremely likely don’t.