If a : b = 2 : 3, then what is the value of (b2 + 2a2) : (b2 - 2a2)?
2021
If a : b = 2 : 3, then what is the value of (b2 + 2a2) : (b2 - 2a2)?
- A.
17 : 1
- B.
18 : 1
- C.
15 : 2
- D.
20 : 11
Attempted by 132 students.
Show answer & explanation
Correct answer: A
Correct answer: 17 : 1
Given a : b = 2 : 3, let a = 2k and b = 3k.
b2 + 2a2 = (3k)2 + 2(2k)2 = 9k2 + 8k2 = 17k2.
b2 - 2a2 = (3k)2 - 2(2k)2 = 9k2 - 8k2 = k2.
Therefore, the required ratio is 17k2 : k2 = 17 : 1.