Answer:
x = 6 ; y = -9
Step-by-step explanation:
8 x + 2 y = 30 ..........equ No 1
7 x + 2 y = 24......... equ No 2
8 x = 30 - 2y
∴ x =
substituting the value of x in equ No 2
7 + 2 y = 24
7 ( 30 -2 y) + 2 y × 8 = 24 × 8
7 × 30 - 14 y + 16 y = 192
210 + 2 y = 192
2 y = 192 - 210
2 y = - 18
∴ y = - 9
put y = -9 , 8 x = 30 - 2 y
8 x = 30 - 2 ( -9)
8 x = 30 - ( -18)
8 x = 48
∴ x = 6
x = 6 ; y = -9
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:
By expanding the previous equation:
The tank capacity and capacity rate of change given in gallons and gallons per minute are, respectivelly:
Since there is no accumulation within the tank, expression is simplified to this:
By rearranging the expression, it is noticed the presence of a First-Order Non-Homogeneous Linear Ordinary Differential Equation:
, where
.
The solution of this equation is:
The salt concentration after 8 minutes is:
The instantaneous amount of salt in the tank is: