Answer:
An equation contains an equal sign so -20 is not an equation, I think it's a typing error
Answer:
a) 
b) 
c)
![Var(X)=E(X^2)-[E(X)]^2= \frac{1}{2}(e^2 -1) -(e-1)^2 = 0.242](https://tex.z-dn.net/?f=Var%28X%29%3DE%28X%5E2%29-%5BE%28X%29%5D%5E2%3D%20%5Cfrac%7B1%7D%7B2%7D%28e%5E2%20-1%29%20-%28e-1%29%5E2%20%3D%200.242)
Step-by-step explanation:
a) what must the value of C be so that f(x) is a probability density function?
In order to be a probability function we need this condition:

And solving the left part of the integral we have:

, so then 
b) find P(X<2)
We can find this probability on this way using the density function:

c) find E(X) and Var(X)
We can find the expected value on this way:
In order to find the Var(X) we need to find the second moment given by:
And now we can use the following definition:
![Var(X)=E(X^2)-[E(X)]^2= \frac{1}{2}(e^2 -1) -(e-1)^2 = 0.242](https://tex.z-dn.net/?f=Var%28X%29%3DE%28X%5E2%29-%5BE%28X%29%5D%5E2%3D%20%5Cfrac%7B1%7D%7B2%7D%28e%5E2%20-1%29%20-%28e-1%29%5E2%20%3D%200.242)
We have to simplify the given expression:

Dividing the terms of the numerator by the given term of denominator individually, we get
= 
By using the laws of exponent,
, we get
= 
= 
= 
= 
Therefore, the simplification of the given expression is
.
So, Option 3 is the correct answer.
Here is an image of (-2,1.5) in a coordinate plane. Hope this helps!