Tiga bilangan memberikan suatu deret geometri. Jika hasil kalinya adalah 216 dan jmlhnya adl 26. Maka rasio deret tsb adalah?
rirismaulidina
![\frac{a}{r} \times a\times ar =a^3=216 \\ a= \sqrt[3]{216}=6 \\ \\ \frac{a}{r} + a+ ar =26 \\ \\ \frac{6}{r} + 6+ 6r=26 \\ \\ 6+6r+6r^2=26r \\ 6r^2-20r+6=0~~~~~dibagi~3 \\ 2r^2-5r+3=0 \\ (2r-1)(r-2)=0 \\ r=1/2~~atau~~r=2](https://tex.z-dn.net/?f=+%5Cfrac%7Ba%7D%7Br%7D+%5Ctimes+a%5Ctimes+ar+%3Da%5E3%3D216+%5C%5C+a%3D+%5Csqrt%5B3%5D%7B216%7D%3D6+%5C%5C++%5C%5C+%5Cfrac%7Ba%7D%7Br%7D+%2B+a%2B+ar+%3D26+%5C%5C+%5C%5C++%5Cfrac%7B6%7D%7Br%7D+%2B+6%2B+6r%3D26+%5C%5C++%5C%5C+6%2B6r%2B6r%5E2%3D26r+%5C%5C+6r%5E2-20r%2B6%3D0%7E%7E%7E%7E%7Edibagi%7E3+%5C%5C+2r%5E2-5r%2B3%3D0+%5C%5C+%282r-1%29%28r-2%29%3D0+%5C%5C+r%3D1%2F2%7E%7Eatau%7E%7Er%3D2 "\frac{a}{r} \times a\times ar =a^3=216 \\ a= \sqrt[3]{216}=6 \\ \\ \frac{a}{r} + a+ ar =26 \\ \\ \frac{6}{r} + 6+ 6r=26 \\ \\ 6+6r+6r^2=26r \\ 6r^2-20r+6=0~~~~~dibagi~3 \\ 2r^2-5r+3=0 \\ (2r-1)(r-2)=0 \\ r=1/2~~atau~~r=2")
0 votes
Thanks 1