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When 21 is subtracted from the square of a number, the result is 4 times the number. Find the negative solution.

1 Answer

3 votes

Answer:

x = - 3

Explanation:

x² - 21 = 4x

x² - 4x - 21 = 0

(x + 3) (x - 7) = 0

x = -3 or x = 7

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