# 7x + y = -2 ……………….. (i) # # -7x + y = -9 …………………… (ii) # (i) 및 (ii) #implies 2y = -11 # #implies y = -11 / 2 # 놓다 # y = -11 / 2 # …에서 #(나는)# #implies 7x-11 / 2 = -2 # 양면을 #2# # implies14x-11 = -4 # #implies 14x = 7 # #implies x = 1 / 2 #