kkbisht
Last Activity: 6 Years ago
Let y=x2+ 1/(x2-1) +5
To find minimum value of y we differentiate y w.r.t x we obtain
dy/dx = 2x + -1.2x/(x2-1)2 .For minima or maxima of y dy/dx=0 => 2x =2x/(x2-1)2 =>x{(x2-1)2 -1}=0
=>x=0 or x2-1=+-1=> x=0, x2=2 => x=0 , x=+-2 Put x=0 , x=2, x=-successively we obtain for x=0
y=0 +1/(0-1) +5 = 4
for x=
2
y= 2+ 1/(2-1) +5 = 8
for x=-2 y=2+1/(2-1) +5 =8
So the minimum vale of the expression x2 + 1/(x2-1) +5 is 4 at x=0