Which are perfect square trinomials? Select two options.x2 − 9x2 −100x2 − 4x + 4x2 + 10x + 25x2 + 15x + 36

A perfect square trinomial has the form (x ± a)² = x² ± 2ax + a². Here, x² − 4x + 4 = (x − 2)² and x² + 10x + 25 = (x + 5)², so the correct choices are C, x² − 4x + 4, and D, x² + 10x + 25. The other expressions do not have both the matching middle term and constant required for a perfect square.

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