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IrinaVladis [17]
3 years ago
15

The focus of a parabola is (3,-7) and the directrix is y = -4.

Mathematics
1 answer:
lidiya [134]3 years ago
3 0

Answer:

  (a)  (x -3)^2 = -6(y +5.5)

Step-by-step explanation:

The equation of a parabola can be written as ...

  (x -h)^2 = 4p(y -k)

where (h, k) is the vertex, and p is the distance from the focus to the vertex.

The vertex is half-way between the focus and directrix, so is ...

  (h, k) = (1/2)((3, -7) +(3, -4)) = (3, -5.5)

The focus is at y=-7, and the vertex is at y=-5.5, so the distance between them is ...

  -7 -(-5.5) = -1.5

Then the equation for the parabola is ...

  (x -3)^2 = 4(-1.5)(y -(-5.5))

  (x -3)^2 = -6(y +5.5) . . . . matches the first choice

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The ratio of girls to boys in the 6th grade is to 6to7 how many girls are there if there are 364total students
Rina8888 [55]

Answer:

168 girls.

Step-by-step explanation:

There are a total of 6 + 7 = 13 'parts'.

So one part = 364 / 13 = 28.

So the number of girls = 6 * 28

= 168.

4 0
3 years ago
What is
ehidna [41]
To find slope subtract the two points in the coordinate (y). We have 8 and 4 so subtract those two. You get 8-4=4. Now start from the same coordinate expect this time subtract (x). Which is 9-3=6. You have 4/6 simplify and you get 2/3. Your slope is 2/3. Hope this helps
5 0
2 years ago
An aircraft emergency locator transmitter (ELT) is a device designed to transmit a signal in the case of a crash. The ACME Manuf
iren [92.7K]

Answer:

a) P(ACME) = 0.7

b) P(ACME/D) = 0.5976

Step-by-step explanation:

Taking into account that ACME manufacturing company makes 70% of the ELTs, if a locator is randomly selected from the general population, the probability that it was made by ACME manufacturing Company is 0.7. So:

P(ACME) = 0.7

Then, the probability P(ACME/D) that a randomly selected locator was made by ACME given that the locator is defective is calculated as:

P(ACME/D) = P(ACME∩D)/P(D)

Where the probability that a locator is defective is:

P(D) = P(ACME∩D) + P(B. BUNNY∩D) + P(W. E. COYOTE∩D)

So, the probability P(ACME∩D) that a locator was made by ACME and is defective is:

P(ACME∩D) = 0.7*0.035 = 0.0245

Because 0.035 is the rate of defects in ACME

At the same way, P(B. BUNNY∩D) and P(W. E. COYOTE∩D) are equal to:

P(B. BUNNY∩D) = 0.25*0.05 = 0.0125

P(W. E. COYOTE∩D) = 0.05*0.08 = 0.004

Finally, P(D) and P(ACME/D) is equal to:

P(D) = 0.0245 + 0.0125 + 0.004 = 0.041

P(ACME/D) = 0.0245/0.041 = 0.5976

5 0
3 years ago
What is the answer for -5(a-6) + 2a
katen-ka-za [31]

Answer:

27a

Step-by-step explanation:

-5(a-6)+2a

-5a+30+2a

-3a+30

27a

7 0
3 years ago
Read 2 more answers
two trains leave the station at the same time one heading west and the other East the westbound train travels at 55 miles per ho
Diano4ka-milaya [45]
Recall your d = rt, distance = rate * time

so... one train goes west and the goes the opposite way... alrite... so... notice, by the time 338 miles have been covered by both, it will have been "t" hours, and whatever "t" is, is the same amount of time the westbound train has been running as well as the eastbound train has been running.

now, let's say, since by "t" hours they've covered 338 altogether, so, if the westbound train has covered say "d" miles, then the eastbound train would have covered the slack from 338 and d, that is, "338 - d".

\bf \begin{array}{lccclll}
&\stackrel{miles}{distance}&\stackrel{mph}{rate}&\stackrel{hours}{time}\\
&------&------&------\\
Westbound&d&55&t\\
Eastbound&338-d&75&t
\end{array}
\\\\\\
\begin{cases}
\boxed{d}=55t\\
338-d=75t\\
----------\\
338-\boxed{55t}=75t
\end{cases}
\\\\\\
338=75t+55t\implies 338=130t\implies \cfrac{338}{130}=t\implies \stackrel{hours}{2.6}=t

so, 2hours and 36 minutes.
8 0
3 years ago
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