Given,
5×5(2n+3)−(25)n+15×(25)n+1−25×52n
Simplifying the expression :
⇒51×52n+3−(25)n+15×(25)n+1−52×52n⇒52n+3+1−[(5)2]n+15×[(5)2]n+1−52n+2⇒52n+4−(5)2n+251×(5)2n+2−52n+2⇒52n+4−52n+252n+2+1−52n+2⇒52n+4−52n+252n+3−52n+2⇒52n+2(52−1)52n+2(5−1)⇒(25−1)4⇒244⇒61.
Hence, 5×52n+3−(25)n+15×(25)n+1−25×52n=61.