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Arlecino [84]
3 years ago
7

How many solutions does x2 = 9 have?​

Mathematics
2 answers:
MrRa [10]3 years ago
5 0
It should have 2 solutions
beks73 [17]3 years ago
4 0

Answer: 2

Step-by-step explanation:

solutions are +3 and -3

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exis [7]
There is no question...???
3 0
3 years ago
A 500-gallon tank initially contains 220 gallons of pure distilled water. Brine containing 5 pounds of salt per gallon flows int
Wittaler [7]

Answer: The amount of salt in the tank after 8 minutes is 36.52 pounds.

Step-by-step explanation:

Salt in the tank is modelled by the Principle of Mass Conservation, which states:

(Salt mass rate per unit time to the tank) - (Salt mass per unit time from the tank) = (Salt accumulation rate of the tank)

Flow is measured as the product of salt concentration and flow. A well stirred mixture means that salt concentrations within tank and in the output mass flow are the same. Inflow salt concentration remains constant. Hence:

c_{0} \cdot f_{in} - c(t) \cdot f_{out} = \frac{d(V_{tank}(t) \cdot c(t))}{dt}

By expanding the previous equation:

c_{0} \cdot f_{in} - c(t) \cdot f_{out} = V_{tank}(t) \cdot \frac{dc(t)}{dt} + \frac{dV_{tank}(t)}{dt} \cdot c(t)

The tank capacity and capacity rate of change given in gallons and gallons per minute are, respectivelly:

V_{tank} = 220\\\frac{dV_{tank}(t)}{dt} = 0

Since there is no accumulation within the tank, expression is simplified to this:

c_{0} \cdot f_{in} - c(t) \cdot f_{out} = V_{tank}(t) \cdot \frac{dc(t)}{dt}

By rearranging the expression, it is noticed the presence of a First-Order Non-Homogeneous Linear Ordinary Differential Equation:

V_{tank} \cdot \frac{dc(t)}{dt} + f_{out} \cdot c(t) = c_0 \cdot f_{in}, where c(0) = 0 \frac{pounds}{gallon}.

\frac{dc(t)}{dt} + \frac{f_{out}}{V_{tank}} \cdot c(t) = \frac{c_0}{V_{tank}} \cdot f_{in}

The solution of this equation is:

c(t) = \frac{c_{0}}{f_{out}} \cdot ({1-e^{-\frac{f_{out}}{V_{tank}}\cdot t }})

The salt concentration after 8 minutes is:

c(8) = 0.166 \frac{pounds}{gallon}

The instantaneous amount of salt in the tank is:

m_{salt} = (0.166 \frac{pounds}{gallon}) \cdot (220 gallons)\\m_{salt} = 36.52 pounds

3 0
3 years ago
Which properties justify the steps taken to solve the system?
Nutka1998 [239]

Answer:

X=-1

Y=1

Step-by-step explanation:

6x-12y

-18

) 6x + 4y

-

-2

Subtract the two equations

6x - 12y - (6x + 4y) = -18 - (-2)

Determine the sign

6x- 12y - 6x- 4y

=-18 + 2

Simplify

-12y

- Ay

=-18 + 2

Solve the equation

Substitute

6×+4

-2

Solve the equation

X=

6 0
2 years ago
of the pets in the pet show 5/6 are cats.4/5 of the calico cats what fraction of the pets are calico cats
Bond [772]
The answer is 0.664 because you have to divide 4/5 and 5/6
3 0
3 years ago
Please!!!!! help me fill the blanks. I really need it!!! It due tomorrow!!!!​
olga nikolaevna [1]

Answer:

The first blank which is in the first row would be 9

The second blank under the 5 is 100

The third blank below the 8 is 160

And the last blank is 240

Step-by-step explanation:

It you do 60 divided by 3, it would be 20, meaning each sweater costs $20.

7 0
3 years ago
Read 2 more answers
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