質問: 0 # using substitution? =======================================================================
回答: #y=3 1/5,x=1/5# #### Explanation: #:.3x+2y=7#---------- (1) #:.x-y+3=0# #:.x-y=-3#---------(2) ----(2)# xx 3#: #:.3x-3y=-9#--------(3) -----#(1)-(3)# : #:.3x+2y=7# #:.3x-3y=-9# #:. 5y=16# #:.y=16/5# #:.y=3 1/5# substitute #y=3 1/5# in #(2)# #:.x-(3 1/5)=-3# #:.x=-3+3 1/5# #:.x=1/5# substitute #y=16/5,x=1/5# in #(1)# #:.3(1/5)+2(16/5)=7# #:.3/5+32/5=7 # #:.35/5=7# #:.7=7#