Răspuns:
Explicație pas cu pas:
3/1·4+3/4·7+3/7·11+....+3/49·52=1/1-1/4+1/4-1/7+1/7-1/11+.....+1/46-1/49+1/49-1/52=1-1/52=(52-1)/52=51/52
1 4/81=85/3^4=17·5/3^4
3^5/13×52/51×17×5/3^4=3×4×5=60
