The paper establishes some generalized weighted Opial-type inequalities, including both the continuous and discrete versions. Applications of the continuous version on fractional derivatives are also given. The original Opial inequality
where , has been generalized to lots of situations and settings over decades. The paper gives some further generalizations to some recent results in the field. The main result is the following generalized weighted Opial-type inequality,
where are continuous positive weight functions on some closed interval and is a fixed point in the interval. The functions and satisfy
where are positive kernels. The function is an integral function involving the weight functions, the kernels, and the indexes and . Some corollaries and the discrete analogues are then provided. Finally the paper discusses applications of the main result on the Riemann-Liouville fractional derivative operators, and corresponding inequalities are established.