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# S1 - How can I tell if a negative number squared is negative or positive? watch

1. I get really confused by whether it is positive or negative. How can I tell.

For example, in E(X^2) for a discrete random variable, if in a table it had x=-3 and P(X=x)=0.2, for E(X^2) in my working out, would that be (9*0.2) or would it be (-9*0.2).

How could I tell?
2. Negative numbers always become positive when they are squared.
3. (Original post by blobbybill)
I get really confused by whether it is positive or negative. How can I tell.

For example, in E(X^2) for a discrete random variable, if in a table it had x=-3 and P(X=x)=0.2, for E(X^2) in my working out, would that be (9*0.2) or would it be (-9*0.2).

How could I tell?
A negative number squared is always a positive number. Always.
4. it be positive
5. (Original post by the bear)
it be positive
Yes ALWAYS...a negative squared is ALWAYS a positive
E.g. -5*-5 = 25
7. (Original post by NothingButWaleed)
Yes ALWAYS...a negative squared is ALWAYS a positive
E.g. -5*-5 = 25
aighhhht for real. another example is -7.2 * -7.2 = 51.84

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