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3 years ago

What is the rate of change of the perimeter of the square at the instant the area is 49 m2?

1 answer:

6 0

Let x = the length of a side of the square (m).
The area is
A = x²
The perimeter is
P = 4x

The rate of change of P with respect to x is
P'(x) = 4 (independent of x)

When A = 49 m², then x = 7 m.
The rate of P is 4.

Answer: 4

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10. A map uses the scale of Zof an inch to represent 3

galben [10]

Answer:

6.25 in

Step-by-step explanation:

Note. It should read 3/4 of an inch.

3/4 in = 3 miles
x in = 25 miles

Cross multiply and solve for x:

x = 25/3*3/4
x = 6.25 in

7 0

2 years ago

(1 point) A fish tank initially contains 15 liters of pure water. Brine of constant, but unknown, concentration of salt is flowi

Drupady [299]

Answer:

a. $\dfrac{dx}{dt} = 6\frac{2}{3} \cdot c$

b. $x(t) = 6\frac{2}{3} \cdot c \cdot t$

c. $c = \dfrac{3}{8} \ g/L$

Step-by-step explanation:

a. The volume of water initially in the fish tank = 15 liters

The volume of brine added per minute = 5 liters per minute

The rate at which the mixture is drained = 5 liters per minute

The amount of salt in the fish tank after t minutes = x

Where the volume of water with x grams of salt = 15 liters

dx = (5·c - 5·c/3)×dt = 20/3·c = $6\frac{2}{3} \cdot c \cdot dt$

$\dfrac{dx}{dt} = 6\frac{2}{3} \cdot c$

b. The amount of salt, x after t minutes is given by the relation

$\dfrac{dx}{dt} = 6\frac{2}{3} \cdot c$

$dx = 6\frac{2}{3} \cdot c \cdot dt$

$x(t) = \int\limits \, dx = \int\limits \left ( 6\frac{2}{3} \cdot c \right) \cdot dt$

$x(t) = 6\frac{2}{3} \cdot c \cdot t$

c. Given that in 10 minutes, the amount of salt in the tank = 25 grams, and the volume is 15 liters, we have;

$x(10) = 25 \ grams(15 \ in \ liters) = 6\frac{2}{3} \times c \times 10$

$6\frac{2}{3} \times c =\dfrac{25 \ grams }{10}$

$c =\dfrac{25 \ g/L }{10 \times 6\frac{2}{3} } = \dfrac{25 \ g/L}{10 \times \dfrac{20}{3} } =\dfrac{3}{200} \times 25 \ g/L= \dfrac{75}{200} \ g/L = \dfrac{3}{8} \ g/L$

$c = \dfrac{3}{8} \ g/L$

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2 years ago

A $40 shirt now selling for $28 is discounted by what percent?

motikmotik

Answer:

30%

Step-by-step explanation:

Think of this as converting a fraction. 28/40 to x/100. You do this because in the situation, 40 is 100 percent of the price. So 28 is x percent of 100.

You multiply 40 by 2.5 to get to 100, so multiply 28 by the same number to get x. 28 * 2.5 = 70.

So 28 is 70 percent of 40. But the question is asking by what percentage it is discounted. If it's now selling for 70%, it has been discounted 30%. So the answer is 30%

3 0

2 years ago

*Please Help*

dmitriy555 [2]

D is the correct answer

good luck

8 0

2 years ago

Given: FJ bisects _HFG, where ZHEJ = (5x+3)° and GFV = (7x-11)°.

goblinko [34]

Answer:

Step-by-step explanation:

7x - 11 = 5x + 3

2x - 11 = 3

2x = 14

x = 7

4 0

2 years ago