Answer:
B ) Negative
Step-by-step explanation:
Given the expression 3xy
when x>0 and y<0
The value of the expression 3xy will be negative.
This is because the product of a positive and negative number will always be negative.
For illustration,
Let x=5>0 and y=-5<0
3xy=3(5)(-5)=-75
NOTE:
Answer:
x(0)=20,y(0)=5
Step-by-step explanation:
We are given that
Tank A contains water=80 gallons
x(0)=20,y(0)=5
Tank B contains water=30 gallons
Rate=4 gallon/min
Concentration of salt is pumped into tank=0.5 pound /gallon of water
Solution pumped from tank A to tank B at the rate=6 gallons/min
Solution pumped from tank B to tank A at the rate=2gallon/min
Solution from tank B is pumped out of the system at the rate=4 gallon/min
We have to find the DE at time t
For x
Rate in=
Rate in=
Rate out=
Rate out=3x/40[/tex]
Rate in-Rate out
For y
Rate in=
Rate in=3/40x
Rate out=
Rate out=y/5
Rate in-Rate out