Question

calcule o 8° termo da P.A (x, x+y/2, y, ...) ME AJUDEM​

Answer 1

Resposta:

$a_1=x\\ a_2={x+y\over2}\\ \\ r=a_2-a_1\\ r={x+y\over2}-x\\ \\ r={x+y-2x\over2}\\ \\ \fbox{ r={-x+y\over2} }\\ \\ a_n=a_8=?\\ a_1=x\\ n=8\\ \\ Termo~~geral\\ \\ a_n=a_1+(n-1)r\\ \\ a_8=x+(8-1)({-x+y\over2}\\ \\ a_8=x+(7)({-x+y\over2})\\ \\ a_8=x-{7x+7y\over2}\\ \\ a_8={2x-7x+7y\over2}\\ \\\fbox{ a_8={-5x+7y\over2} }$