A) \[\left( A,50+46A \right)\]
B) \[\left( A,50+45A \right)\]
C) \[\left( 50,50+46A \right)\]
D) \[\left( 50,50+45A \right)\]
Correct Answer: A
Solution :
\[{{S}_{n}}=50n+\frac{n(n-7)}{2}A\] \[{{T}_{n}}={{S}_{n}}-{{S}_{n-1}}\] \[=50n+\frac{n(n-7)}{2}A-50(n-1)-\frac{(n-1)(n-8)}{2}A\] \[=50+\frac{A}{2}[{{n}^{2}}-7n-{{n}^{2}}+9n-8]\] \[=50+A(n-4)\] \[d={{T}_{n}}-{{T}_{n-1}}\] \[=50+A(n-4)-50-A(n-5)\] \[=A\] \[{{T}_{50}}=50+46A\] \[(d,{{A}_{50}})=(A,50+46A)\]You need to login to perform this action.
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