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The sum `2xx5+5xx9+8xx13+…10` terms isA. `4500`B. `4555`C. `5454`D. None of these |
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Answer» Correct Answer - B `(b)` `S=2xx5+5xx9+8xx13+…10`terms `t_(r )=(3r-1)(4r+1)` `=12r^(2)-r-1` `:.S=sum_(r=1)^(10)(12r^(2)-r-1)` `=12(10.11.21)/(6)-(10.11)/(2)-10` `=10(462-(11)/(2)-1)` `=4555` |
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