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Help you solve math 20/08/2017 at 09:04A=1+2+3+...+49+50
We have 2A=1+2+3+...+49+50+1+2+3+...+49+50
=(1+50)+(2+49)+...+(50+1)
=51+51+...+51
=>A=51.50:2=1275
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Ngân Hà 20/08/2017 at 15:17\(A=\dfrac{\left(1+50\right).50}{2}\)
\(A=\dfrac{51.50}{2}\)
\(A=\dfrac{2550}{2}\)
\(A=1275\)
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