Question

Sa se rezolve ecuatia 1+5+9+....+x=153, in multimea N*.
Ajutati-ma repede va rog!

Answer 1

a1=1
r=4
an=x
Sn=153
an=a1+(n-1)*r
x=1+(n-1)*4
x=1+4n-4
x=4n-3 =>an=4n-3
Sn=$\frac{(a1+an)*n}{2}$
Apoi doar inlocuiesti si faci Δ