If \((20)^{19}\) + \(2(21)(20)^{18} + 3(21)^2 (20)^{17} +\) \(\cdots + 20(21)^{19} =\) \(k(20)^{19}\), then \(k\) is equal to _____ :
If \((20)^{19}\) + \(2(21)(20)^{18} + 3(21)^2 (20)^{17} +\) \(\cdots + 20(21)^{19} =\) \(k(20)^{19}\), then \(k\) is equal to _____ :
Correct Answer: 400
Solution and Explanation
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