Question

sokumon We have
But, ( x=-8 ) gives ( L H S=tan ^{-1}(-7)+tan ^{-1}(-9), ) which is ( n )
while RHS is positive. So, ( x=-8 ) is not possible. Hence, ( x=frac{1}{4} )

# EXAMPLE 23 Solve tan-1(x + 1) + tan (x-1) = tan -tan- 18 31

Solution