1) х^5•х^12 = х^(5+12) = х^17;
4) 40^20 • 40^3 = 40^(20+3) = 40^23;
7) (2/7)^31•(2/7)^6 = (2/7)^(31+6) = (2/7)^37;
10) (-5)^4•(-5)^11 = (-5)^(4+11) = (-5)^15;
13) (-с)^10•(-с)^51 = (-с)^(10+51) = (-с)^61.
