Simplify (az - by)^2 + (bz + ay)^2 - b^2 z^2

The same question, asked 2 times: 18 Jan 2025 Tier II*, 20 Jan 2025 Tier II. Every wording below, oldest first.

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Question 1
18 Jan 2025 Tier II
30 $(5z - 12y)^2 + (12z + 5y)^2 - 144z^2$
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Question 2
20 Jan 2025 Tier II
2 $(5z - 7y)^2 + (7z + 5y)^2 - 49z^2$
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