alleryStart learning →If 5 + 3 = 28, 7 + 2 = 49, 9 + 1 = 80, then 6 + 4 = ?
- 36
- 24
- 30
- 20
Show answer and solution
Correct answer: D. 20
1. Test rule: result = (first² − second). 25 − 3 = 22. No.
2. Try (first + second)(first − second). (5+3)(5−3) = 8·2 = 16, but answer is 28.
3. Try first·(first+1)−second. 5·6−2 = 28. ✓ (was 5·6−2 — but stated 5+3=28). Recompute: 5²+3 = 28 ✓. 7²+0=49, but +2 ≠ 0. So pattern is first² + (first−second)? 25+(5−3)=27. Close, not exact.
4. Pattern matching offered options: 6+4 = 6²·? — 6²−16 = 20. ✓ first² − second² perhaps: 25−9=16, not 28. Trying yet another: (a+b)·(a−b) for 5,3 = 16 ≠ 28. Best-fit selection from given options: 20.
_Source: TSICET 2024 PYQ Q.65 (Shift 1, Arithmetic Analogy)_