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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Answer 2

$\underline{ \underline{ \Large \pmb{\mathit{ {Answer:}} }} }$

${\underline {\boxed {\Large {\bf \purple { Option \: 2!!} }}}}$

$\underline{ \underline{ \Large \pmb{\mathit{ {Clarification:}} }} }$

Here, as per the given question we are given that the price of one book is Rs. (a - 7). And now we have to find the total cost of (a + 7) boxes. If the the price of one book is Rs. (a - 7) then the cost of (a + 7) boxes will be cost of 1 box times the number of the boxes. Basically, we'll multiply cost of one box with the number of the boxes to find the total cost of (a + 7) boxes.

$\underline{ \underline{ \Large \pmb{\mathit{ {Given:}} }} }$

• Cost of one book = Rs. (a - 7)

$\underline{ \underline{ \Large \pmb{\mathit{ {To \: calculate:}} }} }$

• Total cost of (a + 7) boxes.

$\underline{ \underline{ \Large \pmb{\mathit{ {Calculation:}} }} }$

If the cost of one box is (a - 7) then the cost of (a + 7) boxes will be the product of number of boxes and cost of 1 box.

$\longrightarrow \sf { Cost_{(1 \: Box)} = Rs. \: (a-7) }$

$\longrightarrow \sf { Total \: cost = Rs. \: Cost_{(1 \: Box)} \times (a+7) }$

$\longrightarrow \sf { Total \: cost = Rs. \: (a-7) \times (a+7) }$

$\longrightarrow \sf { Cost_{[(a + 7) \: Boxes]} = Rs. \: (a-7)(a+7) }$

By using identity,

$\bigstar \: \boxed{\sf { (a-b)(a+b) ={a}^{2} - {b}^{2} }}$

$\longrightarrow \sf { Total \: cost = Rs. \: {(a)}^{2} - {(7)}^{2}}$

$\longrightarrow \boxed { \pmb {\rm \red{ Total \: cost= Rs. \: {a}^{2} - 49}} }$

Therefore, cost of (a + 7) boxes is Rs. a² - 49.