Tìm `x` biết : `1/[1.6] + 1/[6.11] + … + 1/[(5x+1)(5x+6)] = 10/51`

1 bình luận về “Tìm `x` biết : `1/[1.6] + 1/[6.11] + … + 1/[(5x+1)(5x+6)] = 10/51`”

1. Giải đáp:

   1/(1.6)+1/(6.11)+…+1/((5x+1)(5x+6))=10/51

   => 1/5(5/(1.6)+5/(6.11)+…+5/((5x+1)(5x+6)))=10/51

   => 1/5(1-1/6+1/6-1/11+…+1/(5x+1)1/(5x+6))=10/51

   => 1/5(1-1/(5x+6))=10/51

   => 1/5*(5x+6-1)/(5x+6)=10/51

   => (5x+5)/(5x+6)=10/51:1/5

   => (5x+5)/(5x+6)=10/51*5

   => (5x+5)/(5x+6)=50/51

   => 51(5x+5)=50(5x+6)

   => 255x+255=250x+300

   => 255x-250x=300-255

   => 5x=45

   => x=45:5

   => x=9

   Vậy x=9

   Trả lời