Answer to Problem 61
Using the plus sign in (6.8
)
gives

Equation 125
Then

Equation 126
which says that as
.
But this contradicts the boundary condition that at
.
Therefore (6.7+) does not represent a solution of the boundary value problem (BVP).
Using the minus sign in (6.8
)
gives

Equation 127
Then

Equation 128
which says that as
,
in agreement with the boundary condition
.
Thus it follows that equation (6.7-) gives

Equation 129
with p given by (6.6), as the correct solution of the BVP.