QUESTION 4
i
Easy
A telecom company charges ₹600 for a certain recharge scheme. This prepaid balance is reduced by ₹1 each day after recharge. Write an equation that models the remaining balance b(x) after using the scheme for x days. Explain why it represents linear decay.
SOLUTION
1
Identify initial balance and daily reduction
Initial balance \(= \text{₹} 600\)
Daily reduction \( = \text{₹} 15\)
Daily reduction \( = \text{₹} 15\)
2
Write the equation for remaining balance after \(x\) days
\(b(x) = 600 − 15x\)
This equation represents linear decay because the balance decreases by a fixed amount(₹15) each day.
This equation represents linear decay because the balance decreases by a fixed amount(₹15) each day.
🏆
Final Answer : \(b(x) = 600 − 15x\)
Concept Note
The balance follows a linear function of the form \(b(x) = a − dx\),
where
\(a = \)initial balance
\(d = \)daily deduction
\(x = \)number of days after recharge