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3 years ago

How can the equation of a parabola be derived when given the focus and the directrix?

1 answer:

4 0

The distance between any point (x0,y0) on the parabola and the focus (m,n) is the same as the distance between (x0,y0) and the directrix line ax+by+c. The distance between (x0,y0) and focus (a,b) is \sqrt((x-m)^2+(y-n)^2). The distance between (x0,y0) and ax+by+c is |ax0+by0+c|/\sqrt(m^2+n^2). Equalize these two expressions.

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A restaurant wants to study how well its salads sell. The circle graph shows the sales over the past few days. If 10 of the sala

vova2212 [387]

40%=10
80%=20
100%=25
answer is 25

5 0

3 years ago

What is 5minus e =25

ddd [48]

the answer is 125

5-e

= 5-25

= 125

5 0

3 years ago

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Leiff goes online to buy a new video game. He finds a site that currently has a promotion of 15% off on all orders over $50. Lei

White raven [17]

If the original price tag of the video game is $128, to get its discounted price at 15%, that means what Leiff paid for was (100-15) = 85% of the original price. So, the price of the video game then becomes (0.85 x 128) = $108.80. Since Leiff has to pay an additional 5.3% of the new price, that's (100 + 5.3) = 105.3% of the new price which is (1.053 x 108.8) = $114.57 Adding the shipping fee for the videogame, 114.57 + 4.75 = $119.32 Thus, the total price is <span>$119.32</span>

8 0

3 years ago

Read 2 more answers

Solve 91 - 2 + 7k| +1 = 46

mylen [45]

Answer:

k = -6.29

Step-by-step explanation:

91 - 2 + 7k + 1 = 46

add all like terms

90 + 7k =46

subtract

90 + 7k = 46

-90 -90

------------------------

7k = -44

divide

$\frac{7k}{7}$ = $\frac{-44}{7}$ (these arent fractions thats just how i divide things :))

= -6.28571428571

round to nearest hundredth

k= -6.29

goes up to 9 because 5 makes 8 go up one when rounding

sorry for asking so many questions. hope this helps

7 0

3 years ago

Suppose a particular type of cancer has a 0.9% incidence rate. Let D be the event that a person has this type of cancer, therefo

natita [175]

Answer:

There is a 12.13% probability that the person actually does have cancer.

Step-by-step explanation:

We have these following probabilities.

A 0.9% probability of a person having cancer

A 99.1% probability of a person not having cancer.

If a person has cancer, she has a 91% probability of being diagnosticated.

If a person does not have cancer, she has a 6% probability of being diagnosticated.

The question can be formulated as the following problem:

What is the probability of B happening, knowing that A has happened.

It can be calculated by the following formula

$P = \frac{P(B).P(A/B)}{P(A)}$

Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.

In this problem we have the following question

What is the probability that the person has cancer, given that she was diagnosticated?

P(B) is the probability of the person having cancer, so $P(B) = 0.009$

P(A/B) is the probability that the person being diagnosticated, given that she has cancer. So $P(A/B) = 0.91$

P(A) is the probability of the person being diagnosticated. If she has cancer, there is a 91% probability that she was diagnosticard. There is also a 6% probability of a person without cancer being diagnosticated. So

$P(A) = 0.009*0.91 + 0.06*0.991 = 0.06765$

What is the probability that the person actually does have cancer?

$P = \frac{P(B).P(A/B)}{P(A)} = \frac{0.91*0.009}{0.0675} = 0.1213$

There is a 12.13% probability that the person actually does have cancer.

3 0

3 years ago