Chapter 2: Introduction to Linear Polynomials

Exercise

Question

Question: 4 (i)

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A telecom company charges ₹600 for a certain recharge scheme. This prepaid balance is reduced by ₹15 each day after the recharge.

(i) Write an equation that models the remaining balance b(x) after using the scheme for x days. Explain why it represents linear decay.

Answer

1
Use the initial balance and the constant daily decrease to form an expression for b(x) in terms of x.
Initial balance = ₹600
\text{Decrease in balance over $x$ days = $₹15x$ $\quad$ ${color:#625b5f}[Daily decrease = ₹15]{/color}$}
Hence, the equation for remaining balance after $x$ days = $600 - 15x$
2
Explain why the expression represents linear decay.
Answer: The balance decreases by a constant ₹15 each day. Therefore, the relationship between $b(x)$ and $x$ represents linear decay.
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