1/(2t+5) - 2/(25 -10t) - 4/(4t²-25) =
= 1/(2t+5) + 2/ [ 5(2t-5) ] - 4/ [ (2t -5)(2t+5) ] =
= ( 1*5(2t-5) + 2(2t+5) - 4*5 ) / [ 5(2t-5)(2t+5) ] =
= ( 10t - 25 + 4t +10 -20 ) / [ 5 (2t-5)(2t+5) ] =
= (14t - 35 ) / [ 5(2t - 5)( 2t+5) ] =
= [ 7(2t-5) ] / [ 5(2t-5)(2t+5) ] =
= 7 / [ 5(2t+5) ]=
= 7/ (10t +25)