This DE has characteristic equation
with a repeated root at r = 3/2. Then the characteristic solution is
which has derivative
Use the given initial conditions to solve for the constants:
and so the particular solution to the IVP is
Answer: her call lasted for 26 minutes.
Step-by-step explanation:
Let x represent the number of minutes for which her call lasted.
Rachel purchased a prepaid phone card for $30. Long distance calls cost 6 cents a minute using this card. Converting 6 cents to dollars, it becomes 6/100 = $0.06
This means that the cost of x minutes of long distance call is
0.06 × x = $0.06x.
If the remaining credit on her card is $28.44, it means that
0.06x + 28.44 = 30
0.06x = 30 - 28.44
0.06x = 1.56
x = 1.56/0.06
x = 26
The answer to this question is 6 in. Hope this helps.
