Question

*If the cost of one pen is (a² + 10a + 25) then find the total cost of (a+5) numbers of such pens?*

1️⃣ ₹(a³ +15a²+75a+125)
2️⃣ ₹(a³ +25a²+25a+125)
3️⃣ ₹(a³ -15a²+75a - 125)
4️⃣ ₹(a² +25a+75)​

Answer 1

Answer:

$(1) \: {a}^{3} + 15 {a}^{2} + 75a + 125$

Step-by-step explanation:

Cost of one pen is

$a² + 10a + 25 = (a + 5)(a + 5)$

So,

Cost of (a + 5) pens =

$(a + 5)(a + 5)(a + 5) = {(a + 5)}^{3} = {a}^{3} + 15 {a}^{2} + 75a + 125$