Question

Urgent!! Da-ti click pe intrebare pt. a vedea asa cum trebuie exercitiul! :)

$5^{20+24+28+...+48}$=$25^{n}$

Answer 1

$5^{2(10+12+...+24)}= 25^{n} =>25^{10+12+...+24}=25^n$
n=10+12+...+24
n=2(5+6+7+...+12)
n=2(1+2+3+4+5+6+...+11+12-1-2-3-4)
n=2(12*13/2-10)
n=2*(78-10)
 n=2*68
n=136