oblicz sume 5+9+13+...+105. ciągi..
a1=5an=105r=4--------an=a1+(n-1)*r105=5+(n-1)*4105=5+4n-44n=104n=26
a₁=5
a₂=9
a₃=13
r=a₂-a₁=a₃-a₂=4
an=105
an=a₁+(n-1)r
105=5+(n-1)×4
105=5+4n-4
4n=105-1
n=104;4=26
S₂₆=½(5+105)×26=1430
" Life is not a problem to be solved but a reality to be experienced! "
© Copyright 2013 - 2025 KUDO.TIPS - All rights reserved.
a1=5

an=105
r=4
--------
an=a1+(n-1)*r
105=5+(n-1)*4
105=5+4n-4
4n=104
n=26
a₁=5
a₂=9
a₃=13
r=a₂-a₁=a₃-a₂=4
an=105
an=a₁+(n-1)r
105=5+(n-1)×4
105=5+4n-4
4n=105-1
n=104;4=26
S₂₆=½(5+105)×26=1430