ПОМОГИТЕ, УМОЛЯЮ ДАМ 100 БАЛЛОВ . Решить: 7, 8,9,10,11

71)1/(a+5)-1/(a-5)=(a-5-a-5)/(a²-25)=-10/(a²-25)2)a(a²-25)*[-10/(a²-25)]=-10aa=-39  -10*(-39)=39081)1/5a+1/7a=(7+5)/35a=12/35a2)12/35a * a²/4=3a/35a=7,7  3*7,7/35=3*1,1/5=3,3/5=0,6691)y/5x-5x/y=(y²-25x²)/5xy2)(y-5x)(y+5x)/5xy *1/(y+5x)=(y-5x)/5xyx=1/7;y=1/4(1/4-5/7):(5*1/4*1/7)=-13/28*28/5=-13/5=-2,610(x-3)*(x+3)/(x-3)²=(x+3)/(x-3)x=-21  (-21+3)/(-21-3)=-18/(-24)=3/4=0,751116/a(4-a)-4/a=(16-16+4a)/a(4-a)=4/(4-a)a=-124/(4+12)=4/16=1/4=0,25