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blsea [12.9K]
3 years ago
5

A ceiling light has a cross-section in the shape of a parabola. The parabola is 24 cm wide and 9 cm deep. The lightbulb is locat

ed at the focus of the parabola. How far from the vertex is the lightbulb?

Mathematics
1 answer:
Sedbober [7]3 years ago
4 0

Answer:

  4 cm

Step-by-step explanation:

The equation of a parabola with its vertex at the origin can be written as ...

  y = 1/(4p)x^2

The problem statement tells us that one point on the parabola is (x, y) = (12, 9). We can put these values into the equation and solve for p, the distance from the focus to the vertex.

  9 = 1/(4p)(12^2)

  9×4/144 = 1/p = 1/4 . . . . . . . . multiply by the inverse of the coefficient of 1/p

Then p = 4, and the bulb is 4 cm from the vertex.

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romanna [79]

Answer:

a) \mathrm{E}[\mathrm{T}]=\sum_{\mathrm{H}}^{5} \frac{200}{101-i}

b) \mathrm{Var}[\mathrm{T}]=\sum_{k=1}^{5} \frac{(200)^{2}}{(101-i)^{2}}

Step-by-step explanation:

Given:

The lifetimes of the individual items are independent exponential random variables.

Mean = 200 hours.

Assume, Ti be the time between ( i-1 )st and the ith failures. Then, the T_{i} are independent with \mathrm{T}_{\mathrm{i}} being exponential with rate \frac{(101-i)}{200} .

Therefore,

a) E[T]=\sum_{i=1}^{5} E\left[\tau_{i}\right]

=\sum_{i=1}^{5} \frac{200}{101-i}

\therefore \mathrm{E}[\mathrm{T}]=\sum_{\mathrm{H}}^{5} \frac{200}{101-i}

b)

The variance is given by, \mathrm{Var}[\mathrm{T}]=\sum_{i=1}^{5} \mathrm{Var}[T]

\therefore \mathrm{Var}[\mathrm{T}]=\sum_{k=1}^{5} \frac{(200)^{2}}{(101-i)^{2}}

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The equation
anyanavicka [17]

Answer:

Either A or C I think, Good luck!!!

Step-by-step explanation:

5 0
3 years ago
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9x-4/x=3 ok first lets get the like terms together! So 9x+1x=10x rewrite 10x-4=3 add 4 to both sides 10x=7 then divide 10 7/10=.7 x=.7
Or you can do it this way
9x-4/x=3 combine like terms so times -4 to both sides 3*-4=-12 rewrite 9x+x=-12 combine like term (still got some) 9x+1x=10x rewrite 10x=-12 divide 10 to both sides -12/10=-1.2 rewrite x=-1.2 (I'm like 95% sure it's this one) hope this helps!!! Have a nice nite (Don't be afraid to ask me about details on this or another question)!!!
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Hello,

if f(x)=y=x+3

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f^(-1) (x)=x-3 is the inverse function of f(x).
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