(1/r-5)=(7/2r)

Solution for (1/r-5)=(7/2r) equation:

D( r )

r = 0

r = 0

r = 0

r in (-oo:0) U (0:+oo)

1/r-5 = (7/2)*r // - (7/2)*r

1/r-((7/2)*r)-5 = 0

(-7/2)*r+1/r-5 = 0

1*r^-1-7/2*r^1-5*r^0 = 0

(1*r^0-7/2*r^2-5*r^1)/(r^1) = 0 // * r^2

r^1*(1*r^0-7/2*r^2-5*r^1) = 0

r^1

(-7/2)*r^2-5*r+1 = 0

(-7/2)*r^2-5*r+1 = 0

DELTA = (-5)^2-(1*4*(-7/2))

DELTA = 39

DELTA > 0

r = (39^(1/2)+5)/(2*(-7/2)) or r = (5-39^(1/2))/(2*(-7/2))

r = (39^(1/2)+5)/(-7) or r = (5-39^(1/2))/(-7)

r in { (39^(1/2)+5)/(-7), (5-39^(1/2))/(-7)} 

r in { (39^(1/2)+5)/(-7), (5-39^(1/2))/(-7) }