Com solucioneu el sistema següent: 2x + 3y = -5, -2x -12y = 4

# 2x + 3y = -5 …………….. (i) #

# -2x-12y = 4 ……………. (ii) #

Afegeix # (i) # i # (ii) #

#implies 2x-2x + 3y-12y = -5 + 4 #

#implies -9y = -1 #

# impliesy = 1/9 #

Posa # y = 1/9 # in # (i) #

#implies 2x + 3 * 1/9 = -5 #

#implies 2x + 1/3 = -5 #

#implies 6x + 1 = -15 #

#implies 6x = -16 #

#implies x = -8 / 3 #