2x+5y=25 14x+3y=15 21式×2得4x+10y=50 33式-2式得7y=35y=5把y=5代入1式得2x+25=25x=0方程组的解集为:x=0,y=5
2x+5y=252x=25-5y4x=50-10y4x+3y=1550-10y+3y=1510y-3y=50-157y=35y=52x+25=25x=0
用加减消元法,x=0,y=5.