Răspuns:
Explicație pas cu pas:
a) k-2, k-1, k, k+1, k+2
S=5k=105 ⇒k=21
19, 20, 21 , 22, 23
b) 2k, 2k+2, 2k+4
S=6k+6=168 6k=162 k=27
54, 56, 58
c) a+b=47
1/a+1/b=173 (a+b)/ab=173 47/ab=173 ab=173:47
a=47-b (47-b)b=173/47 47²b-47b-173=0
b1,2=47±√47²-4×47×173/2×47
