Question

Qual o valor da soma dos 15 primeiros termos da PA (2,9,16,...)?

Answer 1

$\mathsf{a_{15}=a_{3}+12r}\\\mathsf{a_{15}=16+12.7}\\\mathsf{a_{15}=16+84=100}$

$\mathsf{s_{15}=\dfrac{15(2+100)}{2}}\\\mathsf{s_{15}=\dfrac{15.102}{2}=15.51=765}$