X^2 -61 =20
X^2= 81x =9 x=-9
hopefully this answer can help you to answer the next question
Answer:
The answer to your question is the letter a) √3/3
Step-by-step explanation:
Data
find tan 30°
Use the triangle 30°-60°-90° (see the picture below)
Tangent is the trigonometric function that relates the Opposite side and the adjacent side.
tan Ф = Opposite side / Adjacent side
-Substitution
tan Ф = 1/√3
or 1/√3 √3/√3 = √3/3
X intercepts are 2 and -1/2
Answer:
See the proof below.
Step-by-step explanation:
For this case we just need to apply properties of expected value. We know that the estimator is given by:

And we want to proof that 
So we can begin with this:

And we can distribute the expected value into the temrs like this:

And we know that the expected value for the estimator of the variance s is
, or in other way
so if we apply this property here we have:

And we know that
so using this we can take common factor like this:

And then we see that the pooled variance is an unbiased estimator for the population variance when we have two population with the same variance.