Question

# Find the sum of $$15$$ terms of the series whose $$n^{th}$$ term is $$4n + 1$$.

Solution

## $${ T }_{ n }=4n+1$$ sum $$=\sum _{ k=1 }^{ 15 }{ \left( 4k+1 \right) }$$$$=\sum _{ k=1 }^{ 15 }{ 4k } +\sum _{ k=1 }^{ 15 }{ \left( 1 \right) }$$$$=4\left[ 1+2+3+4+..........+15 \right]$$$$=4\times \cfrac { 15\times \left( 15+1 \right) }{ 2 } +15$$$$=480+15$$$$=\boxed { 495 }$$Mathematics

Suggest Corrections

0

Similar questions
View More

People also searched for
View More