Question

ex 12 va rog.Dau coroana rasp corect

Answer 1

f(1)=1
f(2)=3
f(3)=5
....
f(2017)=4033
f(2018)=4035
=> s=1+3+5+..+4033+4035
s e progresie aritmetica cu primul termen : 1
si ultimul:4035

suma pt progresia aritmetica e: [(a1+an)•n]/2
a1=primul termen:1
an=ultimul termen:4035
n=nr de termeni
=> s=[(1+4035)•2018]/2=4036•2018/2=4072324

Answer 2

f(1)=2·1-1                                                                                                             f(2)=2·2-1                                                                                                       f(3)=2·3-1                                           .                                                                            .                                                              .                                                                   f(2018)=2·2018-1 ````````````````````````S=2(1+2+3+.....+2018)- 2018S=2·2018·2019/2-2018S=2018·2019-2018S=2018(2019 -1)S=2018²