Question

The product of two successive multiples of 5 is 300. What are the values of these multiples? 5 के 2 लगातार गुणजों का गुणनफल 300 है, तो गुणजों का मूल्य पता करें. *

(A) 25, 30

(B) 10, 15

(C) 30, 35

(D) 15, 20



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Answer 1

Answer:

15, 20

Step-by-step explanation:

Let those multiples are 5a & 5(a + 1).

Their product = 300

=> 5a x 5(a + 1) = 300

=> 25a(a + 1) = 300

=> a(a + 1) = 300/25 = 12

=> a² + a - 12 = 0

=> a² + 4a - 3a - 12 = 0

=> a(a + 4) - 3(a + 4) = 0

=> (a + 4)(a - 3) = 0

=> a = 3 (ignore -ve 4)

Therefore, multiples are:

5a = 5(3) = 15

5(a+1) = 5(3+1) = 20

Answer 2

Answer:

• Option (C) 15 , 20

Step-by-step explanation:

Let those multiples are 5R & 5(R + 1).

According to question,

● The product of two successive multiples of 5 is 300.

↪ 5R × 5(R + 1) = 300

↪ 25R(R + 1) = 300

↪ 25R² + 25R = 300

↪ 25R² + 25R - 300 = 0

↪ R² + R - 12 = 0

↪ R² + 4R - 3R - 12 = 0

↪ R(R + 4) - 3(R + 4) = 0

↪ (R + 4) (R - 3) = 0

[ Ignore negative term. ]

↪R = 3

Now,

↪ 5R = 5 × 3 = 15

↪ 5(R + 1) = 5(3 + 1) = 5(4) = 20

Hence,

• Multiples are 15 and 20.