Question

Determinați nr k dacă 169+2*169+3*169+....+49*169=k la puterea a 2a.

Answer 1

k²=169+169*2+169*3+...+49*169
k²=169(1+2+3+...+49)
k²=169*$\frac{49*50}{2}$
k²=169*49*25
k=13*7*5⇒k=455