Respuestas

  • Usuario de Brainly
2012-04-24T06:07:17+02:00

7x-4y=5 ------------------ 7X = 5 + 4Y --------------- X = (5 + 4Y) /7 ------ ecuación (1)

9x+8y=13 ----------------------------------------------------------------------- ecuación (2)


(1) en (2)

 

X = 

9 (5 + 4Y) /7 + 8y = 13

45 + 36Y

--------- + 8Y = 13

     7


45 + 36Y

--------- = 13 - 8Y

     7


45 + 36Y = 7 (13 - 8Y)

45 + 36Y = 91 - 56Y

36Y + 56Y = 91 - 45

92Y = 46

 

Y = 46/92

 

Y = 1/2