Multiple choice

If 2 = 5, 4 = 18, 6 = 39, then 10 is

  1. 45

  2. 81

  3. 100

  4. 105
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pattern: n² + 1. For n=2: 2²+1=5. For n=4: 4²+1=17≈18 (approximation). For n=6: 6²+1=37≈39. Following the pattern n²+1 exactly for n=10: 10²+1=101. However, the options suggest a different pattern: n×(n+1)/2 + n, or perhaps n² + n/2 for odd n. Let me reconsider: 2×2.5=5, 4×4.5=18, 6×6.5=39, 10×10.5=105. The pattern is n×(n+0.5).

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