B=3+32+33+...+350
3B=32+33+...+351
3B-B=(32+33+...+351)-(3+32+33+...+350)
2B=351-3
B=\(\dfrac{3^{51}-3}{2}\)
B=3+32+33+...+350
3B=32+33+...+351
3B-B=(32+33+...+351)-(3+32+33+...+350)
2B=351-3
B=\(\dfrac{\text{3^{51}-3}}{2}\)
\(B=3+3^2+3^3+...+3^{50}\\ 3B=3^2+3^3+3^4+...+3^{51}\\ 3B-B=\left(3^2+3^3+3^4+...+3^{51}\right)-\left(3+3^2+3^3+...+3^{50}\right)\\ 2B=3^{51}-3\\ \Rightarrow B=\dfrac{3^{51}-3}{2}\)
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