What is the sum of two consecutive odd numbers, the difference of whose…
2024
What is the sum of two consecutive odd numbers, the difference of whose squares is 56?
- A.
30
- B.
28
- C.
34
- D.
32
Attempted by 1 students.
Show answer & explanation
Correct answer: B
Concept: For any two numbers that differ by a fixed amount, the difference of their squares can be found directly from the identity a2 − b2 = (a − b)(a + b) — it equals the product of their difference and their sum. Since two consecutive odd numbers always differ by 2, this identity turns the given condition on their squared difference into a simple linear equation in one unknown.
Application:
Let the smaller consecutive odd number be x; then the next is x + 2.
The difference of their squares is (x + 2)2 − x2 = 4x + 4.
Set 4x + 4 = 56 and solve: 4(x + 1) = 56 ⇒ x + 1 = 14 ⇒ x = 13.
Thus the numbers are 13 and 15, and their sum is 13 + 15 = 28.
Verification: 152 − 132 = 225 − 169 = 56, so the solution is consistent.