Răspuns :
a+a+2+a+4+a+6=72
4a+12=72
4a=72-12
4a=60
a=60:4
a=15.(primul nr)
a+2=17(al doilea nr)
a+4=19(al treilea nr)
a+6=21(al patrulea nr)
4a+12=72
4a=72-12
4a=60
a=60:4
a=15.(primul nr)
a+2=17(al doilea nr)
a+4=19(al treilea nr)
a+6=21(al patrulea nr)
a+b+c+d=72
2k+1+2k+3+2k+5+2k+7=72
8k+16=72
8k=72-16
8k=56
k=7
a=2k+1=2*7+1=14+1=15
b=2k+3=2*7+3=14+3=17
c=2k+5=2*7+5=14+5=19
d=2k+7=2*7+7=14+7=21
2k+1+2k+3+2k+5+2k+7=72
8k+16=72
8k=72-16
8k=56
k=7
a=2k+1=2*7+1=14+1=15
b=2k+3=2*7+3=14+3=17
c=2k+5=2*7+5=14+5=19
d=2k+7=2*7+7=14+7=21