word problem

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lula lula
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word problem

Find a negative real number such that the square of the sum of the number and 3 is equal to 441.  (If there are two correct answers, either answer can be entered.)

McGenius McGenius
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Re: word problem

x = the number

(x + 3)² = 441   ← square of sum of number and 3 equals 441
(x + 3)(x + 3) = 441   ← squared binomial
x² + 6x + 9 = 441   ← foil method
x² + 6x - 432 = 0   ← subtracted 441
(x + 24)(x - 18) = 0   ← factored
x + 24 = 0    or   x  - 18 = 0   ← set to zero
x = -24   or   x = 18   ← solved

The negative real number is -24

*McGenius*