Подбираем знаменатель и сперва смотрим что получим в первой части, потом уже вторую подбираем числа; в решении видно, что одинаково две части; ____________________________________ а) 1/4+1/*=*+*/12; ___________________________________
1))) 1/4+ 1/3= 3/12+ 4/12; ___________________________________ (1*3)/(4*3)+ (1*4)/(3*4)=7/12; ___________________________________
3/12+ 4/12= 7/12; ___________________________________ 7/12=7/12. 2))) 1/4+ 1/3= 1/2+ 1/12; ___________________________________ (1*3)/(4*3)+ (1*4)/(3*4) = (1*6)/(2*6)+ 1/12; ___________________________________ 3/12+4/12= 6/12+1/12; ___________________________________ 7/12= 7/12; ___________________________________ 3))) 1/4+ 1/6= 3/12+ 2/12; ___________________________________ (1*3)/(4*3)+ (1*2)/6*2)= 5/12; ___________________________________
3/12+ 2/12= 5/12; ___________________________________ 5/12= 5/12; 4))))) 1/4+ 1/48= 1/48+ 3/12; ___________________________________ (1*12)/(4*12)+ 1/48= 1/48+ (3*4)/(12*4); ___________________________________ 12/48+ 1/48= 1/48+ 12/48; ___________________________________ 13/48= 13/48; ___________________________________
б) 1/5+1/*=*+*/20; ___________________________________ 1))) 1/5+ 1/4= 7/20+ 2/20; ___________________________________ (1*4)/(5*4)+ (1*5)/(4*5)= 9/20; ___________________________________ 4/20+ 5/20= 9/20; ___________________________________ 9/20= 9/20; 2))) 1/5+ 1/20= 1/10+ 3/20; ___________________________________ ((1*4)/(5*4)+ 1/20= (1*2)/(10*2)+ 3/20; ___________________________________ 4/20+ 1/20= 2/20+ 3/20; ___________________________________ 5/20= 5/20; сокращаем на 5 ___________________________________ 1/4= 1/4; ___________________________________ 3))) 1/5+ 1/40= 3/40+ 3/20; ___________________________________ (1*8)/(5*8)+ 1/40= 3/40+ (3*2)/(20*20); ___________________________________ 8/40+ 1/40= 3/40+ 6/40; ___________________________________ 9/40= 9/40; ___________________________________
в) 1/6+1/*=*+*/30; ___________________________________ 1/6+ 1/5= 1/5+ 5/30; ___________________________________ (1*5)/(6*5)+ (1*6)/(5*6)= (1*6)/(5*6)+ 5/30; ___________________________________ 5/30+ 6/30= 6/30+ 5/30; ___________________________________ 11/30= 11/30; ___________________________________ 2))) 1/6+ 1/60= 1/60+ 5/30; ___________________________________ (1*10)/(6*10)+ 1/60= 1/60+ (5*2)/(30*2); ___________________________________ 10/60+ 1/60= 1/60+ 10/60; ___________________________________ 11/60= 11/60; ___________________________________ 3))) 1/6+ 1/90= 4/90+ 4/30; ___________________________________ (1*15)/(6*15)+ 1/90= 4/90+ (4*3)/(30*3); ___________________________________ 15/90+ 1/90= 4/90+ 12/90; ___________________________________ 16/90= 16/90; ___________________________________ сокращаем на 2 ___________________________________ 8/45= 8/45;