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3 years ago

Please help its math

Mathematics

1 answer:

Masteriza [31]3 years ago

4 0

Answer:

the 3rd

Step-by-step explanation:

because n^2+3n+2n simplifies to n(n+5), which is not equivalent to 6n

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One kind of hard candy sells for $.89 per kilogram another sells for $1.10 per kilogram how many kilograms of each kind a need t

Furkat [3]

Answer:

20kg of $0.89 candy

10kg of $1.10 candy

Step-by-step explanation:

Candy 1 = 0.89 per kg

Candy 2 = 1.10 per kg

Total kilogram, kg = 30

Let candy 1 = x ; candy 2 = (30 - x) ;

0.89x + 1.10(30 - x) = 0.96(30)

0.89x + 33 - 1.10x = 28.8

0.89x - 1.10x = 28.8 - 33

-0.21x = - 4.2

x = 4.2 / 0.21

x = 20

20kg of $0.89 candy

(30 - x) = (30 - 20) = 10kg

10kg of $1.10 candy

4 0

3 years ago

Write an integer that represents 14,000 feet below sea level

masha68 [24]

- 14,000 feet hopefully....

4 0

2 years ago

You are a lifeguard and spot a drowning child 60 meters along the shore and 40 meters from the shore to the child. You run along

sukhopar [10]

Answer:

The lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.

Step-by-step explanation:

This is a problem of optimization.

We have to minimize the time it takes for the lifeguard to reach the child.

The time can be calculated by dividing the distance by the speed for each section.

The distance in the shore and in the water depends on when the lifeguard gets in the water. We use the variable x to model this, as seen in the picture attached.

Then, the distance in the shore is d_b=x and the distance swimming can be calculated using the Pithagorean theorem:

$d_s^2=(60-x)^2+40^2=60^2-120x+x^2+40^2=x^2-120x+5200\\\\d_s=\sqrt{x^2-120x+5200}$

Then, the time (speed divided by distance) is:

$t=d_b/v_b+d_s/v_s\\\\t=x/4+\sqrt{x^2-120x+5200}/1.1$

To optimize this function we have to derive and equal to zero:

$\dfrac{dt}{dx}=\dfrac{1}{4}+\dfrac{1}{1.1}(\dfrac{1}{2})\dfrac{2x-120}{\sqrt{x^2-120x+5200}} \\\\\\\dfrac{dt}{dx}=\dfrac{1}{4} +\dfrac{1}{1.1} \dfrac{x-60}{\sqrt{x^2-120x+5200}} =0\\\\\\ \dfrac{x-60}{\sqrt{x^2-120x+5200}} =\dfrac{1.1}{4}=\dfrac{2}{7}\\\\\\ x-60=\dfrac{2}{7}\sqrt{x^2-120x+5200}\\\\\\(x-60)^2=\dfrac{2^2}{7^2}(x^2-120x+5200)\\\\\\(x-60)^2=\dfrac{4}{49}[(x-60)^2+40^2]\\\\\\(1-4/49)(x-60)^2=4*40^2/49=6400/49\\\\(45/49)(x-60)^2=6400/49\\\\45(x-60)^2=6400\\\\$

$x$

As $d_b=x$ , the lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.