(x – 7)(x + 3) =

Use the distributive property to multiply each term in the first factor by each term in the second: x·x = x², x·3 = 3x, −7·x = −7x, and −7·3 = −21. Combine the middle terms, 3x − 7x = −4x, to get x² − 4x − 21. This matches choice B, x² − 4x − 21.

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