(10t^5 - 5t^11)(10t^3 + 2t^2)

Раскрываем скобки: 10t^5 * 10t^3 = 100t^8, 10t^5 * 2t^2 = 20t^7, -5t^11 * 10t^3 = -50t^14, -5t^11 * 2t^2 = -10t^13. Складываем: -50t^14 - 10t^13 + 100t^8 + 20t^7.