Hidden rule a @ b = a^2 + b: find it from the examples and apply

This type of question, asked 4 times: 12 Sep 2025 S3, 13 Sep 2025 S3, 17 Sep 2025 S2, 20 Sep 2025 S1. All 4 questions below, oldest first.

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Question 1
12 Sep 2025 S3
19 $If 5 @ 3 = 28 and 4 @ 2 = 18, then what is 6 @ 4?$
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Question 2
13 Sep 2025 S3
15 $If 5 @ 1 = 26, 3 @ 4 = 13, then 6 @ 2 = ?$
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Question 3
17 Sep 2025 S2
17 $If 4 @ 3 = 19 and 2 @ 5 = 9, then 5 @ 2 = ?$
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Question 4
20 Sep 2025 S1
18 $If 9 @ 1 = 82 and 6 @ 2 = 38, what is the value of 7 @ 3?$
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Question 1