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TS EAMCET · Maths · Functions

If f1=0 and f(n+1)-f(n)=5nnN then f(n)=

  1. A 52n2+n
  2. B 52n2-n
  3. C 533n2-n
  4. D 544n2-1(n-1)
Verified Solution

Answer & Solution

Correct Answer

(B) 52n2-n

Step-by-step Solution

Detailed explanation

f1=0 fn+1-fn=5n, ∀n∈N Put n=1 f2-f1=5×1 ⇒f2=5 Put n=2 f3-f2=5×2 ⇒f3=10+5 Put n=3 f4-f3=5×3 f4=15+0+5 Similarly, fn=5+10+15+.....+5n-1 =51+2+.....+n-1 =5nn-12 =52n2-n