Question 624190
(21 + r)^2

(21 + r)(21 + r)

21 * 21 = 441

21 * r = 21r

r * 21 = 21r

r * r = r^2


441 + 21r + 21 r + r^2


Combine like terms:

21r + 21r = 42r


The Answer:


441 + 42r + r^2



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