(p/q)-(q/p)=21/10
then
(4p/q)+(4q/p)=?

• let p/q = a
  so q/p = 1/a
  so according to the question,
  (a - 1/a) = 21/10
  after squaring both side we get,
  (a - 1/a)^2 = 441/100
  so,
  (a + 1/a)^2 - 4*a*1/a = 441/100
  so,
  (a + 1/a)^2 = 441/100 + 4 = 841/100
  so,
  (a + 1/a) = sqrt(841/100) = 2.9
  as we want 4*(a + 1/a)
  which is 2.9*4 = 11.6
• 9 years agoHelpfull: Yes(6) No(2)
• 11.6 or 58/5
• 9 years agoHelpfull: Yes(1) No(2)
• can you xpain me how you got it?
• 9 years agoHelpfull: Yes(1) No(1)
• let (p/q)=a,(q/p)=b
  a-b=21/10=>(a-b)^2=(a+b)^2-4ab
  (21/10)^2 = (a+b)^2-4*1,(since ab=(p/q)(q/p)=1)
  sqrt( (441/100) +4)= (a+b)
  (a+b)=2.9
  4a+4b=4(2.9)=11.6 (ans)
• 9 years agoHelpfull: Yes(1) No(2)