Langkah 3: Menyelesaikan sebutan yang sama
\(\begin{aligned} &(3k-1)(3k+1)+\dfrac{9(k+6)^2}{2}\\\\ &=[(3k)(3k)+(3k)(1)\\&\quad+(-1)(3k)+(-1)(1)]\\ &\quad+\dfrac{9[(k+6)(k+6)}{2}\longrightarrow\text{Kembangkan}\\\\ &=[(3k)(3k)+(3k)(1)\\&\quad+(-1)(3k)+(-1)(1)]\\ &\quad+\dfrac{9[(k)(k)+(k)(6)+(6)(k)+(6)(6)]}{2}\\\\ &=9k^2+3k-3k-1\\ &\quad+\dfrac{9(k^2+6k+6k+36)}{2} \end{aligned}\)
\(\begin{aligned} &=9k^2-1+\dfrac{9(k^2+12k+36)}{2}\\ &=9k^2-1+\dfrac{9}{2}k^2+54k+162\\&=9k^2+\dfrac{9}{2}k^2+54k-1+162\\ &=\dfrac{27}{2}k^2+54k+161. \end{aligned}\)
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