Question

(progresie aritmetica )Cum se rezolva ex : a1 + a5 = 16 ; r = 3 .. aflati primi 10 termeni 

Answer 1

a5=a1+(n-1)r
n=5
=>a5=a1+4*3=a1+12
a1+a1+12=16
2a1=4
a1=2
S10=(a1+a10)*10/2
S10=(2+29)*10/2=31*10/2=31*5=155
a10=a1+(10-1)*3=2+9*3=2+27=29