Deret 4 + 10 +16 +.....+k = 374. Jadi tentukan nilai K adalah...

Deret 4 + 10 +16 +…..+k = 374. Jadi tentukan nilai K adalah…

Jawaban Terkonfirmasi

$a=4,b=4,U_n=k\ U_n=a+(n-1)b\ k=4+(n-1)6\ frac{k-4}{6}+1=n\ frac{k-4+6}{6}=n\ frac{k+2}{6}=n\ S_n=frac{n}{2}(a+U_n)\ 374=frac{frac{k+2}{6}}{2}(4+k)\ 374=frac{k+2}{12}(4+k)\ 4488=(k+2)(k+4)\ k^2+6k+8=4488\ k^2+6k-4480=0\ k_{1,2}=frac{-6 underline{+}sqrt{6^2-4(1)(-4480)}}{2}\ k_{1,2}=frac{-6 underline{+}sqrt{17956}}{2}\ k_{1,2}=frac{-6 underline{+}134}{2}\ k_{1,2}=-3 underline{+}67\k_1=-3+67=64\k_2=-3-67=-70(tidak memenuhi)$