সমাধান - জ্যামিতিক ধারা

সিরিজের সাধারণ রূপ খুঁজে পেতে, প্রথম পদ: $$a=800$$ এবং সাধারণ অনুপাত: $$r=0.7$$ জ্যামিতিক সিরিজের সূত্রে প্লাগ করুন:

$$a_1=800$$

$$a_2=a_1·r^{n-1}=800\cdot {0.7}^{2-1}=800\cdot {0.7}^1=800\cdot 0.7=560$$

$$a_3=a_1·r^{n-1}=800\cdot {0.7}^{3-1}=800\cdot {0.7}^2=800\cdot 0.48999999999999994=391.99999999999994$$

$$a_4=a_1·r^{n-1}=800\cdot {0.7}^{4-1}=800\cdot {0.7}^3=800\cdot 0.3429999999999999=274.3999999999999$$

$$a_5=a_1·r^{n-1}=800\cdot {0.7}^{5-1}=800\cdot {0.7}^4=800\cdot 0.24009999999999995=192.07999999999996$$

$$a_6=a_1·r^{n-1}=800\cdot {0.7}^{6-1}=800\cdot {0.7}^5=800\cdot 0.16806999999999994=134.45599999999996$$

$$a_7=a_1·r^{n-1}=800\cdot {0.7}^{7-1}=800\cdot {0.7}^6=800\cdot 0.11764899999999996=94.11919999999996$$

$$a_8=a_1·r^{n-1}=800\cdot {0.7}^{8-1}=800\cdot {0.7}^7=800\cdot 0.08235429999999996=65.88343999999996$$

$$a_9=a_1·r^{n-1}=800\cdot {0.7}^{9-1}=800\cdot {0.7}^8=800\cdot 0.05764800999999997=46.118407999999974$$

$$a_{10}=a_1·r^{n-1}=800\cdot {0.7}^{10-1}=800\cdot {0.7}^9=800\cdot 0.04035360699999998=32.282885599999986$$