dydx+√(x2−1)(y2−1)xy=0
⇒y√y2−1dy=−√x2−1xdx
⇒∫y√y2−1dy=−∫x2−1x√x2−1dx
Let y2−1=t2⇒2ydy=2tdt
∴∫dt=−∫x√x2−1dx+∫1x√x2−1dx
⇒t=−√x2−1+sec−1x+C
⇒√y2−1=−√x2−1+sec−1x+C
The curve passes through (1,1).
∴C=0
Hence, the curve is √y2−1=−√x2−1+sec−1x
Also, (√2,k) lies on the curve.
⇒√k2−1=−1+π4
⇒k2=(π4−1)2+1
⇒k2=m+1, m∈(0,1)
⇒k=±√m+1
⇒[k]=1 or −2
∴ The largest value of |[k]|=2