А+4/а²-10а+25-а+2/а²-25 при а=7,5 решите

А+4/а²-10а+25-а+2/а²-25 =a+4/(a-5)²-a+2/(a-5)(a+5)=((a+4)(a+5)-(a+2)(a-5))/(a-5)²(a+5)=(a²+5a+4a+20-a²+5a-2a+10)/(a-5)²(a+5)=(12a+30)/(a-5)²(a+5)=(12·7,5+30)/(7,5-5)²(7,5+5)=(90+30)/6,25·12,5=120/78,125=120/78 1/8=120/625/8=120·8/625=24·8/125=192/125