Question

*The price of one box is (a - 7) Rs. What is the total cost of (a + 7) boxes?*

1️⃣ ₹(a² - 14a + 49)
2️⃣ ₹(a² - 49)
3️⃣ ₹(a² + 14a + 49)
4️⃣ ₹(a² + 49)​

Answer 1

Answer:

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Step-by-step explanation:

Given : Cost of one box = Rs. (a-7)

To find : Cost of (a+7) boxes

Solution :

$Cost_{(1 \: box)} = (a - 7) \\ \\ Total \: \: cost = cost_{(1 \: box)} \times (a + 7) \\ \\ Total \: \: cost = (a - 7)\times (a + 7) \\ \\ Cost_{(a + 7) \: boxes} = (a - 7)(a + 7) \\ \\ Using \: \: identity \: (x - y)(x + y) = x {}^{2} - {y}^{2} \\ \\ Total \: cost = (a) {}^{2} - (7) {}^{2} \\ \\ \bold\red{Total \: Cost =a {}^{2} - 49}$

∴ Total cost of (a+7) boxes is Rs. a²-49

Answer 2

Answer:

then the cost of (a+7) is a^2 - 49