2+5+8+..........+ l = 950 Urutan keberapakan l ??? Plisss bantu aku jangan Lupa cara nya

a = 2
b = 3
Sn = 950
[tex]S_n = \frac{n}{2}(2a+(n-1)b) \\ 950=\frac{I}{2}(2(2)+(I-1)3) \\ 1900=I(4+3I-3) \\ 1900 = I(3I+1) \\ 3I^2+I=1900 \\ 3I^2+I-1900 = 0 \\ (3I+76)(I-25)=0 \\ I=-\frac{76}{3}$ (TM)$ \\ I=25[/tex]