Question

resolvendo o sistema encontramos : (se puderem botem calculo.bjj)$\left \{ {{x+y=9} \atop {x-y=3}} \right.$

A)S= [(12,-3)] C)S={(6,3)]
B)S={(-12,3)] D)S=[(-6,-3)]

Answer 1

x  +  y = 9

x  -  y  = 3

2x = 12

x = 12/2    x = 6

6 + y = 9

y = 9 - 6   y = 3

resposta letra C  S = {( 6, 3)}