At x→1,
x15−1x10−1 becomes 00 form
Now,
limx→1x15−1x10−1
=limx→1x15−115x10−110
Divide and multiply by (x−1), we get
=limx→1[x15−115x−1×x−1x10−110]
=limx→1[x15−115x−1]limx→1[x10−110x−1]
=15(1)15−110(1)10−1[∵limx→1xn−anx−a=nan−1]
=32