সমাধান - জ্যামিতিক ধারা

সিরিজের সাধারণ রূপ খুঁজে পেতে, প্রথম পদ: $$a=120$$ এবং সাধারণ অনুপাত: $$r=0.7$$ জ্যামিতিক সিরিজের সূত্রে প্লাগ করুন:

$$a_1=120$$

$$a_2=a_1·r^{n-1}=120\cdot {0.7}^{2-1}=120\cdot {0.7}^1=120\cdot 0.7=84$$

$$a_3=a_1·r^{n-1}=120\cdot {0.7}^{3-1}=120\cdot {0.7}^2=120\cdot 0.48999999999999994=58.79999999999999$$

$$a_4=a_1·r^{n-1}=120\cdot {0.7}^{4-1}=120\cdot {0.7}^3=120\cdot 0.3429999999999999=41.15999999999999$$

$$a_5=a_1·r^{n-1}=120\cdot {0.7}^{5-1}=120\cdot {0.7}^4=120\cdot 0.24009999999999995=28.811999999999994$$

$$a_6=a_1·r^{n-1}=120\cdot {0.7}^{6-1}=120\cdot {0.7}^5=120\cdot 0.16806999999999994=20.16839999999999$$

$$a_7=a_1·r^{n-1}=120\cdot {0.7}^{7-1}=120\cdot {0.7}^6=120\cdot 0.11764899999999996=14.117879999999996$$

$$a_8=a_1·r^{n-1}=120\cdot {0.7}^{8-1}=120\cdot {0.7}^7=120\cdot 0.08235429999999996=9.882515999999995$$

$$a_9=a_1·r^{n-1}=120\cdot {0.7}^{9-1}=120\cdot {0.7}^8=120\cdot 0.05764800999999997=6.917761199999997$$

$$a_{10}=a_1·r^{n-1}=120\cdot {0.7}^{10-1}=120\cdot {0.7}^9=120\cdot 0.04035360699999998=4.842432839999997$$