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4 years ago

5

A school of salmon was swimming in the river 5 feet below the surface. To escape a hungry bear, they went down another 3 feet. W

hat is the position of the salmon now relative to the surface?

2 answers:

bekas [8.4K]4 years ago

4 0

Answer:

-8

Step-by-step explanation:

the reason that it s negitive 8 instead of postive 8 is because it say 8 feet below sea level meaning negitive below decresed 8 feet

garik1379 [7]4 years ago

3 0

Answer:

8 Feet below the surface

Step-by-step explanation:

If the salmon were initially 5 feet below the surface, and then travelled down an additional 3 feet from the initial 5, then the new position would be 8 feet down relative to the surface.

You can write this as -5 + -3 = -8, assuming that 0 represents surface level.

Cheers.

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How many tenths are there in four fifths?

sleet_krkn [62]

So to find how many tenths, or 1/10's, there are in four fifths, or 4/5, divide 4/5 by 1/10.

$\frac{4}{5} \div \frac{1}{10}$

Now, remember that <u>dividing by a number is equivalent to multiplying by its reciprocal</u>. To find the reciprocal, just flip the numerator and denominator around. In this case, 1/10 would become 10/1. Flip 1/10 to its reciprocal, change the sign to multiplication, and multiply numerators with numerators and denominators with denominators:

$\frac{4}{5}\times \frac{10}{1}=\frac{40}{5}=8$

<u>In short, there are 8 tenths in four fifths.</u>

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3 years ago

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(5+2×8)/6=x(4+6) what is the value of x ?

pogonyaev

Answer:

Step-by-step explanation:

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3 years ago

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What is the answer to Pi?

Alex73 [517]

Answer:

pi = 3.141592653589793238462643

Step-by-step explanation:

that's how we came up with pi simply being 3.14 and why pi day is 3/14 every year

4 0

3 years ago

Integrate the following problem:

vazorg [7]

Answer:

$\displaystyle \frac{2 \cdot sin2x-cos2x}{5e^x} + C$

Step-by-step explanation:

The integration by parts formula is: $\displaystyle \int udv = uv - \int vdu$

Let's find u, du, dv, and v for $\displaystyle \int e^-^x \cdot cos2x \ dx$ .

$u=e^-^x$
$du=-e^-^x dx$

$dv=cos2x \ dx$
$v= \frac{sin2x}{2}$

Plug these values into the IBP formula:

$\displaystyle \int e^-^x \cdot cos2x \ dx = e^-^x \cdot \frac{sin2x}{2} - \int \frac{sin2x}{2} \cdot -e^-^x dx$
$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{e^-^x sin2x}{2} - \int \frac{sin2x}{2} \cdot -e^-^x dx$

Now let's evaluate the integral $\displaystyle \int \frac{sin2x}{2} \cdot -e^-^x dx$ .

Let's find u, du, dv, and v for this integral:

$u=-e^-^x$
$du=e^-^x dx$
$dv=\frac{sin2x}{2} dx$
$v=\frac{-cos2x}{4}$

Plug these values into the IBP formula:

$\displaystyle \int -e^-^x \cdot \frac{sin2x}{x}dx = -e^-^x \cdot \frac{-cos2x}{4} - \int \frac{-cos2x}{4}\cdot e^-^x dx$

Factor 1/4 out of the integral and we are left with the exact same integral from the question.

$\displaystyle \int -e^-^x \cdot \frac{sin2x}{x}dx = -e^-^x \cdot \frac{-cos2x}{4} + \frac{1}{4} \int cos2x \cdot e^-^x dx$

Let's substitute this back into the first IBP equation.

$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{e^-^x sin2x}{2} - \Big [ -e^-^x \cdot \frac{-cos2x}{4} + \frac{1}{4} \int cos2x \cdot e^-^x dx \Big ]$

Simplify inside the brackets.

$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{e^-^x sin2x}{2} - \Big [ \frac{e^-^x \cdot cos2x}{4} + \frac{1}{4} \int cos2x \cdot e^-^x dx \Big ]$

Distribute the negative sign into the parentheses.

$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{e^-^x sin2x}{2} - \frac{e^-^x \cdot cos2x}{4} - \frac{1}{4} \int cos2x \cdot e^-^x dx$

Add the like term to the left side.

$\displaystyle \int e^-^x \cdot cos2x \ dx + \frac{1}{4} \int cos2x \cdot e^-^x dx= \frac{e^-^x sin2x}{2} - \frac{e^-^x \cdot cos2x}{4}$
$\displaystyle \frac{5}{4} \int e^-^x \cdot cos2x \ dx = \frac{e^-^x sin2x}{2} - \frac{e^-^x \cdot cos2x}{4}$

Make the fractions have common denominators.

$\displaystyle \frac{5}{4} \int e^-^x \cdot cos2x \ dx = \frac{2e^-^x sin2x}{4} - \frac{e^-^x \cdot cos2x}{4}$

Simplify this equation.

$\displaystyle \frac{5}{4} \int e^-^x \cdot cos2x \ dx = \frac{2e^-^x sin2x - e^-^x cos2x}{4}$

Multiply the right side by the reciprocal of 5/4.

$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{2e^-^x sin2x - e^-^x cos2x}{4} \cdot \frac{4}{5}$

The 4's cancel out and we are left with:

$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{2e^-^x sin2x - e^-^x cos2x}{5}$

Factor $e^-^x$ out of the numerator.

$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{e^-^x(2 \cdot sin2x-cos2x)}{5}$

Simplify this by using exponential properties.

$\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{2 \cdot sin2x-cos2x}{5e^x}$

The final answer is $\displaystyle \int e^-^x \cdot cos2x \ dx = \frac{2 \cdot sin2x-cos2x}{5e^x} + C$ .

7 0

3 years ago

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The following function is probability mass function. f left-parenthesis x right-parenthesis equals StartFraction 2x plus 1Over 2

lora16 [44]

Answer:

a) Mean = 2.6

B) Variance = 9.2

Step-by-step explanation:

We are given the following probability mass function in the question:

$F(x) = \dfrac{2x+1}{25}, x = 0,1,2,3,4$

a) Mean of random variable

$\mu = \displaystyle\sum x_iF(x_i)\\\\=0(\dfrac{1}{25}) + 1(\dfrac{2+1}{25}) + 2(\dfrac{4+1}{25}) + 3(\dfrac{6+1}{25}) + 4(\dfrac{8+1}{25})\\\\=\dfrac{3+10+21+36}{25} = \dfrac{70}{25} = 2.8$

b) Variance of the random variable

$\sigma^2 = \displaystyle\sum x_i^2F(x_i)\\\\=0^2(\dfrac{1}{25}) + 1^2(\dfrac{2+1}{25}) + 2^2(\dfrac{4+1}{25}) + 3^2(\dfrac{6+1}{25}) + 4^2(\dfrac{8+1}{25})\\\\=\dfrac{3+20+63+144}{25} = \dfrac{230}{25} = 9.2$

6 0

3 years ago