x - obecny wiek Bartka y - obecny wiek taty [latex]left { {{x+y = 45} atop {y - x = 25}} ight[/latex] Metoda podstawiania [latex]left { {{x+y = 45} atop {y = 25+x}} ight [/latex] [latex]left { {{x+25+x = 45} atop {y = 25+x}} ight [/latex] [latex]left { {{2x+25 = 45} atop {y = 25+x}} ight [/latex] [latex]left { {{2x = 45 - 25} atop {y = 25+x}} ight [/latex] [latex]left { {{2x = 20 / : 2} atop {y = 25+x}} ight [/latex] [latex]left { {{x = 10} atop {y = 25+10}} ight [/latex] [latex]left { {{x = 10} atop {y = 35}} ight [/latex] Metoda przeciwnych wspólczynników [latex]left { {{x+y = 45} atop {- x + y = 25}} ight[/latex] ___________________ [latex]2y = 70 / :2[/latex] [latex]y = 35[/latex] [latex]x+y = 45[/latex] [latex]x+35 = 45[/latex] [latex]x = 45 - 35[/latex] [latex]x = 10[/latex] [latex]left { {{x = 10} atop {y = 35}} ight [/latex] Odp. Bartek ma 10 lat, a jego tata 35 lat.
