Ответ:

№1

Объяснение:

1) 100t²/(100t²-9) + 9/(100t²-9) = (100t²+9)/(100t²-9)

2) (100t²+9)(100t²-9) - 60t/( (10t-3)(10t+3) ) =

(100t²+9)/(100t²-9) - 60t/(100t²-9) =

(100t²+9-60t)/(100t²-9) =

(100t²-60t+9)/( (10t-3)(10t+3) ) =

(10t-3)²/( (10t-3)(10t+3) ) = (10t - 3)/(10t + 3)