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lara31 [8.8K]
3 years ago
14

Read this E[2X^2 â€" Y].

Mathematics
1 answer:
djyliett [7]3 years ago
6 0

Looks like a badly encoded/decoded symbol. It's supposed to be a minus sign, so you're asked to find the expectation of 2<em>X </em>² - <em>Y</em>.

If you don't know how <em>X</em> or <em>Y</em> are distributed, but you know E[<em>X</em> ²] and E[<em>Y</em>], then it's as simple as distributing the expectation over the sum:

E[2<em>X </em>² - <em>Y</em>] = 2 E[<em>X </em>²] - E[<em>Y</em>]

Or, if you're given the expectation and variance of <em>X</em>, you have

Var[<em>X</em>] = E[<em>X</em> ²] - E[<em>X</em>]²

→   E[2<em>X </em>² - <em>Y</em>] = 2 (Var[<em>X</em>] + E[<em>X</em>]²) - E[<em>Y</em>]

Otherwise, you may be given the density function, or joint density, in which case you can determine the expectations by computing an integral or sum.

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*PLZ HELP*...Given the following word problems, write an inequality that models the problem, then solve and check...
Ber [7]

Answer:

Maximum $11.28

Step-by-step explanation:

Let remaining money be x

  • 13.72 + x ≤ 25
  • x ≤ 25 - 13.72
  • x ≤ 11.28

He can spend maximum of $11.28 in September

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3 years ago
Four times a number, subtracted from nine, is twice the number. How do I solved this?
Natalija [7]

4x - 9 = 2x


Solve for x.

4x = 2x + 9

2x = 9

x = 4.5

We can plug 4.5 into the original equation to verify if it's correct.

4x - 9 = 2x

4(4.5) - 9 = 2(4.5)

18 - 9 = 9

The equation is true, and so x = 4.5

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3 years ago
What is the length of the dotted line? Round to the nearest hundredth.
prohojiy [21]

Answer:3.75

Step-by-step explanation:

I think that’s it

5 0
2 years ago
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What is the equation, in standard form of the parabola that contains the following points? (-2,18), (0,2), (4,42)
Vladimir79 [104]

Answer: y = 3x^{2} - 2x + 2

Step-by-step explanation:

The equation in standard form of a parabola is given as :

y = ax^{2}  + bx + c

The points given are :

( -2 , 18 ) , ( 0,2) , ( 4 , 42)

This means that :

x_{1} = -2

x_{2} = 0

x_{3} = 4

y_{1} = 18

y_{2} = 2

y_{3} = 42

All we need do is to substitute each of this points into the equation , that is , x_{1} and y_{1} will be substituted to get an equation , x_{2} and y_{2} will be substituted to get an equation and x_{3} , y_{3} will also be substituted to get an equation also.

Starting with the first one , we have :

y = ax^{2}  + bx + c

18 = a[(-2)^{2}] + b (-2) + c

18 = 4a  - 2b + c

Therefore :

4a - 2b + c = 18 ................ equation 1

substituting the second values , we have

2 = a (0) + b ( 0) + c

2 = c

Therefore c = 2   ............... equation 2

also substituting the third values , we have

42 = a[(4)^{2}] + b (4) + c

42 = 16a + 4b + c

Therefore

16a + 4b + c = 42  ........... equation 3

Combining the three equations we have:

4a - 2b + c = 18 ................ equation 1

c = 2   ............... equation 2

16a + 4b + c = 42  ........... equation 3

Solving the resulting linear equations:

substitute equation 2 into equation 1 and equation 3 ,

substituting into equation 1 first we have

4a - 2b + 2 = 18

4a - 2b = 16

dividing through by 2 , we have

2a - b = 8 ............... equation 4

substituting c = 2 into equation 3 , we have

16a + 4b + c = 42

16a + 4b + 2 = 42

16a + 4b = 40

dividing through by 4 , we have

4a + b = 10 ................ equation 5

combining equation 4 and 5 , we have

2a - b = 8 ............... equation 4

4a + b = 10 ................ equation 5

Adding the two equations to eliminate b , we have

6a = 18

a = 18/6

a = 3

Substituting a = 3 into equation 4 to find the value of b , we have

2(3) - b = 8

6 - b = 8

b = 6 - 8

b = -2

Therefore :

a = 3 , b = -2 and c = 2

Substituting these values into the equation of parabola in standard form , we have

y = 3x^{2} - 2x + 2

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Zolol [24]

Answer:

2 hours

Step-by-step explanation:

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