Verified answer

Answer:

[tex](question - 1) \\ (6 - xy) \: \: (6 + xy) \\ = 6(6 + xy) -xy(6 + xy) \\ = 36 + 6xy - {(xy) }^{2} \\ = 36 - {x }^{2} - {y}^{2} [/tex]

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[tex](question - 2) \\ - {7}^{2} + {18x}^{2} + {3x}^{2} - {5x}^{2} \\ = {21x}^{2} - \: {12x}^{2} \\ = {9x}^{2} [/tex]

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Step-by-step explanation:

The answer is given above in photo