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2 years ago

4

The loudest insect on Earth is the African cicada. It produces sounds as loud as 105 decibels at 20 inches away. The blue whale

is the loudest mammal on Earth. The call of the blue whale can reach levels up to 83 decibels louder than the African cicada. How loud are the calls of the blue whale?

1 answer:

Gre4nikov [31]2 years ago

3 0

You are told that the cicada is 105 decibels. You are also told that the blue whale is 83 decibels louder than the cicadas. Using the word “more” tells you that you are adding. So you add 105+83=188 decibels

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A savings account compounds interest, ata rate of 22%, once a year. George puts $750 in the account as the principal. How can ge

insens350 [35]

Answer:

there is your answer

Step-by-step explanation:

750 time 22%

22%=.22

750 x .22=

3 0

2 years ago

F(x)=3x 2 +9f, left parenthesis, x, right parenthesis, equals, 3, x, squared, plus, 9 and g(x)=\dfrac{1}{3}x^2-9g(x)= 3 1 x 2

34kurt

Answer:

$f(g(x)) = \frac{1}{3}x^4 - 18x^2 + 252$

$g(f(x)) = 3x^4 + 18x^2 + 18$

<em>f(x) and g(x) and not inverse functions</em>

Step-by-step explanation:

Given

$f(x) = 3x^2 + 9$

$g(x) = \dfrac{1}{3}x^2 - 9$

Required

Determine f(g(x))

Determine g(f(x))

Determine if both functions are inverse:

Calculating f(g(x))

$f(x) = 3x^2 + 9$

$f(g(x)) = 3(\frac{1}{3}x^2 - 9)^2 + 9$

$f(g(x)) = 3(\frac{1}{3}x^2 - 9)(\frac{1}{3}x^2 - 9) + 9$

Expand Brackets

$f(g(x)) = (x^2 - 27)(\frac{1}{3}x^2 - 9) + 9$

$f(g(x)) = x^2(\frac{1}{3}x^2 - 9) - 27(\frac{1}{3}x^2 - 9) + 9$

$f(g(x)) = \frac{1}{3}x^4 - 9x^2 - 9x^2 + 243 + 9$

$f(g(x)) = \frac{1}{3}x^4 - 18x^2 + 252$

Calculating g(f(x))

$g(x) = \dfrac{1}{3}x^2 - 9$

$g(f(x)) = \frac{1}{3}(3x^2 + 9)^2 - 9$

$g(f(x)) = \frac{1}{3}(3x^2 + 9)(3x^2 + 9) - 9$

$g(f(x)) = (x^2 + 3)(3x^2 + 9) - 9$

Expand Brackets

$g(f(x)) = x^2(3x^2 + 9) + 3(3x^2 + 9) - 9$

$g(f(x)) = 3x^4 + 9x^2 + 9x^2 + 27 - 9$

$g(f(x)) = 3x^4 + 18x^2 + 18$

Checking for inverse functions

$f(x) = 3x^2 + 9$

Represent f(x) with y

$y = 3x^2 + 9$

Swap positions of x and y

$x = 3y^2 + 9$

Subtract 9 from both sides

$x - 9 = 3y^2 + 9 - 9$

$x - 9 = 3y^2$

$3y^2 = x - 9$

Divide through by 3

$\frac{3y^2}{3} = \frac{x}{3} - \frac{9}{3}$

$y^2 = \frac{x}{3} - 3$

Take square root of both sides

$\sqrt{y^2} = \sqrt{\frac{x}{3} - 3}$

$y = \sqrt{\frac{x}{3} - 3}$

Represent y with g(x)

$g(x) = \sqrt{\frac{x}{3} - 3}$

Note that the resulting value of g(x) is not the same as $g(x) = \dfrac{1}{3}x^2 - 9$

<em>Hence, f(x) and g(x) and not inverse functions</em>

4 0

2 years ago

As part of Kayla's exercise program,she either runs 6miles/day or rides her bike 10 miles/day.Her new goal is to cover a minimum

poizon [28]

6(15) + 10b > = 200
90 + 10b > = 200
10b > = 200 - 90
10b > = 110
b > = 110/10
b > = 11

so she can do 15 days of running plus 11 days of biking....which totals 26 days

8 0

2 years ago

What is the time period of a loan for $2,500 at 12% exact interest if the amount of interest is $118.36? Round to the next highe

Marianna [84]

I believe it's 144 days.

Hope this helped!

5 0

2 years ago

Read 2 more answers

A rectangular storage container with an open top is to have a volume of 10m3. Thelength of its base is twice the width. Material

frutty [35]

Answer:

$163.54

Step-by-step explanation:

Volume of rectangular container = 10m^3

Length = 2(width)

Material for the base cost $10 per square meter

Material for the side cost $6 per square meter

Volume = L*B*H

L= 2W

V = (2W).W. H

10 = 2W^2.H

H = 10 /2W^2

H = 5/W^2

Let C(w) = cost function

C(w) = 10(L.W) + 6(2.L.H + 2.W.H)

= 10(2W.W) + 6(2.2W.H + 2.W.H)

= 10(2W^2) + 6(4W.H + 2.W.H)

= 10(2W^2) + 6(4W*5/W^2 + 2.W*5/W^2)

= 20W^2 + 6(20/W + 10/W)

= 20W^2 + 6((10+20)/W)

= 20W^2 + 6(30/W)

C(w) = 20W^2 + 180/W

To find the minimum value, differentiate C with respect to w

C'(w) = 40W - 180/W^2

Put C'(w) = 0

0 = 40W - 180/W^2

40W = 180/W^2

40W^3 = 180

W^3 = 180/40

W^3 = 4.5

W = cube rt(4.5)

W = 1.65m

C = 20(1.65)^2 + 180/1.65

C = 54.45 + 109.09

C= $163.54

Minimum cost = $163.54

6 0

2 years ago