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krok68 [10]
2 years ago
10

(-9) ÷(-2)=? Please help​

Mathematics
2 answers:
Cerrena [4.2K]2 years ago
8 0

Answer:

4.5

Step-by-step explanation:

Andru [333]2 years ago
5 0

Answer:

(-9) ÷(-2)=4.5

Step-by-step explanation:

type it in a calculator !!

you will get the result.

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On a cloudy day, Yong Sun needed to know the height of a window in a building. Yong Sun positioned a mirror on the ground betwee
const2013 [10]
Its a ratio problem

height/34.15 = 1.89/.2288
4 0
3 years ago
. Which ordered pairs in the form (x, y) are solutions to the equation 7x – 5y = 28?
Brut [27]

we know that

If a ordered pair (x,y) is a solution of the equation, then the ordered pair must satisfy the equation

we have the equation

7x-5y=28

Let's verify all the cases to determine the solution to the problem.

<u>case A)</u> point (-6,-14)

Substitute the values of x and y in the equation

x=-6\\y=-14

7(-6)-5(-14)=28

-42+70=28

28=28 -------> is  true

therefore

The point  (-6,-14) is a solution of the equation

<u>case B)</u> point (-1,-7)

Substitute the values of x and y in the equation

x=-1\\y=-7

7(-1)-5(-7)=28

-7+35=28

28=28 -------> is  true

therefore

The point  (-1,-7) is  a solution of the equation

<u>case C)</u> point (4,10)

Substitute the values of x and y in the equation

x=4\\y=10

7(4)-5(10)=28

28-50=28

-22=28 -------> is not true

therefore

The point (4,10) is not a solution of the equation

<u>case D)</u> point (7,9)

Substitute the values of x and y in the equation

x=7\\y=9

7(7)-5(9)=28

49-45=28

4=28 -------> is not true

therefore

The point  (7,9) is not a solution of the equation

therefore

<u>the answer is </u>

(-6,-14)

(-1,-7)

8 0
3 years ago
Read 2 more answers
2. Which is a solution of 2(t-1)+3t 9p+6-5p
insens350 [35]

Answer:

3t9p + 2t - 5p + 4

Step-by-step explanation:

4 0
3 years ago
A tank contains 100 L of water. A solution with a salt con- centration of 0.4 kg/L is added at a rate of 5 L/min. The solution i
Fantom [35]

Answer:

a) (dy/dt) = 2 - [3y/(100 + 2t)]

b) The solved differential equation gives

y(t) = 0.4 (100 + 2t) - 40000 (100 + 2t)⁻¹•⁵

c) Concentration of salt in the tank after 20 minutes = 0.2275 kg/L

Step-by-step explanation:

First of, we take the overall balance for the system,

Let V = volume of solution in the tank at any time

The rate of change of the volume of solution in the tank = (Rate of flow into the tank) - (Rate of flow out of the tank)

The rate of change of the volume of solution = dV/dt

Rate of flow into the tank = Fᵢ = 5 L/min

Rate of flow out of the tank = F = 3 L/min

(dV/dt) = Fᵢ - F

(dV/dt) = (Fᵢ - F)

dV = (Fᵢ - F) dt

∫ dV = ∫ (Fᵢ - F) dt

Integrating the left hand side from 100 litres (initial volume) to V and the right hand side from 0 to t

V - 100 = (Fᵢ - F)t

V = 100 + (5 - 3)t

V = 100 + (2) t

V = (100 + 2t) L

Component balance for the amount of salt in the tank.

Let the initial amount of salt in the tank be y₀ = 0 kg

Let the rate of flow of the amount of salt coming into the tank = yᵢ = 0.4 kg/L × 5 L/min = 2 kg/min

Amount of salt in the tank, at any time = y kg

Concentration of salt in the tank at any time = (y/V) kg/L

Recall that V is the volume of water in the tank. V = 100 + 2t

Rate at which that amount of salt is leaving the tank = 3 L/min × (y/V) kg/L = (3y/V) kg/min

Rate of Change in the amount of salt in the tank = (Rate of flow of salt into the tank) - (Rate of flow of salt out of the tank)

(dy/dt) = 2 - (3y/V)

(dy/dt) = 2 - [3y/(100 + 2t)]

To solve this differential equation, it is done in the attached image to this question.

The solution of the differential equation is

y(t) = 0.4 (100 + 2t) - 40000 (100 + 2t)⁻¹•⁵

c) Concentration after 20 minutes.

After 20 minutes, volume of water in tank will be

V(t) = 100 + 2t

V(20) = 100 + 2(20) = 140 L

Amount of salt in the tank after 20 minutes gives

y(t) = 0.4 (100 + 2t) - 40000 (100 + 2t)⁻¹•⁵

y(20) = 0.4 [100 + 2(20)] - 40000 [100 + 2(20)]⁻¹•⁵

y(20) = 0.4 [100 + 40] - 40000 [100 + 40]⁻¹•⁵

y(20) = 0.4 [140] - 40000 [140]⁻¹•⁵

y(20) = 56 - 24.15 = 31.85 kg

Amount of salt in the tank after 20 minutes = 31.85 kg

Volume of water in the tank after 20 minutes = 140 L

Concentration of salt in the tank after 20 minutes = (31.85/140) = 0.2275 kg/L

Hope this Helps!!!

8 0
2 years ago
Help please I-ready please
svlad2 [7]

Answer:

(5, 180)

Step-by-step explanation:

You use 5(z) and multiply it by 36 to get 180(y)

3 0
2 years ago
Read 2 more answers
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