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Ludmilka [50]
3 years ago
14

y varies directly as x and inversely as the square of z. y = 65 when x = 80 and z=4. Find y when x= 18 and z=3.

Mathematics
1 answer:
sdas [7]3 years ago
8 0

Answer: y

=

18

Explanation:

As

y

varies directly as

x

, we have

y

∝

x

. Also it varies inversely as square of

z

, which means

y

∝

1

z

2

.

Hence,

y

∝

x

z

2

or

y

=

k

×

x

z

2

, where

k

is a constant.

Now when

x

=

80

and

z

=

4

,

y

=

10

, so

10

=

k

×

80

4

2

=

k

×

80

16

=

5

k

Hence

k

=

10

5

=

2

and

y

=

2

x

z

2

.

So when

x

=

36

and

z

=

2

,

y

=

2

×

36

2

2

=

72

4

=

18

Step-by-step explanation:

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A bacteria culture starts with 12,000 bacteria and the number doubles every 50 minutes.
Vlada [557]

Answer:

a)  y=12000(2)^{\frac{t}{50}}

b)  Approx. 27,569 bacteria

c)  About 103 minutes

Step-by-step explanation:

a)

This will follow exponential modelling with form of equation shown below:

y=Ab^{\frac{t}{n}}

Where

A is the initial amount (here, 12000)

b is the growth factor (double, so growth factor is "2")

n is the number of minutes in which it doubles, so n = 50

Substituting, we get our formula:

y=Ab^{\frac{t}{n}}\\y=12000(2)^{\frac{t}{50}}

b)

To get number of bacteria after 1 hour, we have to plug in the time into "t" of the formula we wrote earlier.

Remember, t is in minutes, so

1 hour = 60 minutes

t = 60

Substituting, we get:

y=12000(2)^{\frac{t}{50}}\\y=12000(2)^{\frac{60}{50}}\\y=12000(2)^{\frac{6}{5}}\\y=27,568.76

The number of bacteria after 1 hour would approximate be <u>27,569 bacteria</u>

<u></u>

c)

To get TIME to go to 50,000 bacteria, we will substitute 50,000 into "y" of the equation and solve the equation using natural logarithms to get t. Shown below:

y=12000(2)^{\frac{t}{50}}\\50,000=12,000(2)^{\frac{t}{50}}\\4.17=2^{\frac{t}{50}}\\Ln(4.17)=Ln(2^{\frac{t}{50}})\\Ln(4.17)=\frac{t}{50}*Ln(2)\\\frac{t}{50}=\frac{Ln(4.17)}{Ln(2)}\\\frac{t}{50}=2.06\\t=103

After about 103 minutes, there will be 50,000 bacteria

4 0
3 years ago
The first term of a geometric series is a/b^2, and the common ratio is b/a^2. Find the next five terms of the geometric sequence
PSYCHO15rus [73]
Here it is in order (2nd to 6th):
1/ab, 1/a^3, b/a^5, b^2/a^7, b^3/a^9

Hope this helps!
5 0
3 years ago
Read 2 more answers
a computer and printer a totoal cost $1132 the cost of the computer is three times the cost of the ptinter
zavuch27 [327]
Use a system of equations

C+P=1132
3P=C

Substitute C in first equation as
3P+P=1132
Simplify
4P=1132
Solve
P=1132/4
P=283

NOW SOLVE FOR C SUBSTITUTING P VALUE IN FIRST EQUATION

C+283=1132
C=1132-283
C=849


Printer = 283$
Computer = 849$
3 0
2 years ago
120 is the same as 394 fewer than Z
SpyIntel [72]

Answer:

z=514

Step-by-step explanation:

120=z-394

+394. +394

514=z

Hope this helps

8 0
3 years ago
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ryzh [129]
The answer is 36 units squared
8 0
3 years ago
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