(a) Given, $(n):1 + 3 + 5 + ... + (2n - 1) = n^{2}$ $P(1):1 = 1$(true) Let $P(k) = 1 + 3 + 5 + ... + (2k - 1) = k^{2}$ $\therefore P(k + 1) = 1 + 3 + 5 + ... + (2k - 1) + 2k + 1$ $= k^{2} + 2k + 1 = (k + 1)^{2}$ So, it holds for all $n$.
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