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lyudmila [28]
4 years ago
12

Assume that y varies inversely with x. if y=7 when x=-2, find y when x=7

Mathematics
1 answer:
melisa1 [442]4 years ago
8 0

Answer:

y=-2

Step-by-step explanation:

The formula for inverse variation is

xy =k

if y=7 when x=-2, we can substitute these numbers in to find k

(-2)(7) =k

-14 =k

The equation becomes

xy = -14

Let x =7

7y = -14

Divide each side by 7

7y/7 = -14/7

y = -2

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Find all real zeros of f(x) = 2x^2 +5x-18 algebraically.
den301095 [7]
2x2-5x-18=0

Two solutions were found :

x = -2
x = 9/2 = 4.500
Step by step solution :

Step 1 :

Equation at the end of step 1 :

(2x2 - 5x) - 18 = 0
Step 2 :

Trying to factor by splitting the middle term

2.1 Factoring 2x2-5x-18

The first term is, 2x2 its coefficient is 2 .
The middle term is, -5x its coefficient is -5 .
The last term, "the constant", is -18

Step-1 : Multiply the coefficient of the first term by the constant 2 • -18 = -36

Step-2 : Find two factors of -36 whose sum equals the coefficient of the middle term, which is -5 .

-36 + 1 = -35
-18 + 2 = -16
-12 + 3 = -9
-9 + 4 = -5 That's it

Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above, -9 and 4
2x2 - 9x + 4x - 18

Step-4 : Add up the first 2 terms, pulling out like factors :
x • (2x-9)
Add up the last 2 terms, pulling out common factors :
2 • (2x-9)
Step-5 : Add up the four terms of step 4 :
(x+2) • (2x-9)
Which is the desired factorization

Equation at the end of step 2 :

(2x - 9) • (x + 2) = 0
Step 3 :

Theory - Roots of a product :

3.1 A product of several terms equals zero.

When a product of two or more terms equals zero, then at least one of the terms must be zero.

We shall now solve each term = 0 separately

In other words, we are going to solve as many equations as there are terms in the product

Any solution of term = 0 solves product = 0 as well.
4 0
3 years ago
Read 2 more answers
A gym's membership cost $280 in 2019. Now, it is $160. Which expression equals the percent of change?
kherson [118]

Answer:

1/2%

Step-by-step explanation:

4 0
3 years ago
Changes in airport procedures require considerable planning. Arrival rates of aircrft are important factors that muct be taken i
Irina18 [472]

Answer:

a) 0.1558

b) 0.7983

c) 0.1478

Step-by-step explanation:

If we suppose that small aircraft arrive at the airport according to a <em>Poisson process</em> <em>at the rate of 5.5 per hour</em>  and if X is the random variable that measures the number of arrivals in one hour, then the probability of k arrivals in one hour is given by:

\bf P(X=k)=\displaystyle\frac{(5.5)^ke^{-5.5}}{k!}

(a) What is the probability that exactly 4 small aircraft arrive during a 1-hour period?

\bf P(X=4)=\displaystyle\frac{(5.5)^4e^{-5.5}}{4!}=0.1558

(b) What is the probability that at least 4 arrive during a 1-hour period?

\bf P(X\geq4)=1-P(X

(c) If we define a working day as 12 hours, what is the probability that at least 75 small aircraft arrive during a working day?

If we redefine the time interval as 12 hours instead of one hour, then the rate changes from 5.5 per hour to 12*5.5 = 66 per working day, and the pdf is now

\bf P(X=k)=\displaystyle\frac{(66)^ke^{-66}}{k!}

and we want <em>P(X ≥ 75) = 1-P(X<75)</em>. But

\bf P(X

hence

P(X ≥ 75) = 1-0.852 = 0.1478

7 0
4 years ago
What is the solution
Volgvan

Answer:

B: (x-6)^2=0

Step-by-step explanation:

5 0
4 years ago
Help help legit answers only
Ne4ueva [31]

Answer:

x ≈ 46.7°

Step-by-step explanation:

Using the sine ratio in the right triangle

sin x = \frac{opposite}{hypotenuse} = \frac{OP}{NP} = \frac{4}{5.5} , then

x = sin^{-1} (\frac{4}{5.5} ) ≈ 46.7° ( to the nearest tenth )

6 0
3 years ago
Read 2 more answers
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