Question

QUESTÃO EM ANEXO, TEMA : PROGRESSÃO ARITIMÉTICA

Answer 1

Ola Joao 

PA

a1 = l
a2 = 4l
a3 = l²

razão
r = a2 - a1 = 4l - l = 3l
r = a3 - a2 = l² - 4l 

l² - 4l = 3l
l² = 7l

l = 7

PA

a1 = 7
a2 = 4*7 = 28
a3 = 7² = 49

.

Answer 2

$PA~~ \{ x, 4x, x^2\}\\\\\\ a_2-a_1 = a_3-a_2 \to~~~~substitua ~~os~~valores:\\\\\\ 4x-x=x^2-4x\to \\\\ x^2-4x-4x+x=0\to \\\\ x^2-7x=0 \to~~~~Por~~Evid\^encia:\\\\ x(x-7)=0\to\\\\ \large\boxed{x=0}\\x-7\to~~\large\boxed{x=7}\\\\\\ [Considere~~ apenas~~o ~~valor~~inteiro]$





$Verificando:\\\\\\Lado\to~~ x = 7~um\\\\ Perimetro\to~~ 4x \to~~ 4*7 \to~~ 28 ~um\\\\ Area \to~~ x \to~~ 7 = 49~ um\\\\\\\\ PA~~\{7, 28, 49\}\to~~~~raz\~ao~~igual~~21$