Question

a última questão
me ajudem é pra amanhã​

Answer 1

Resposta:

SUBSTITUIÇÃO:

$\left \{ {{x+y=25} \atop {x-y=3}} \right. \\\\x = 25 - y\\\\(25 - y) - y = 3\\\\25 - y - y = 3\\\\-2y = 3 - 25\\\\-2y = -22\\\\2y = 22\\\\y = 11$

$x - y = 3\\\\x - 11 = 3\\\\x = 3 + 11\\\\x = 14$

ADIÇÃO:

$\left \{ {{x+y=25} \atop {x-y=3}} \right. \\\\x + x + y + (-y) = 25 + 3\\\\2x = 28\\\\x = 14\\\\\\\\x - y = 3\\\\14 - y = 3\\\\-y = 3 - 14\\-y = -11\\y = 11$