Question

Determine o 25° termo da P.A (7,18,29)

Answer 1

a1 = 7
a2 =18
a3 = 29
r = 18 - 7 = 11 ***
a25 =  a1 + 24r = 7 + 24 ( 11 )  = 7 + 264 = 271 ***resposta

Answer 2

$\mathsf{ a_n=a_1+(n-1)\cdot r}$

$\mathsf{ a_{25}=7+(25-1)\cdot11}$

$\mathsf{ a_{25}=7+24\cdot11}$

$\mathsf{a_{25}=7+264 }$

$\boxed{\boxed{\mathsf{ a_{25}= 271}}}$