In this paper, we determine the primitive solutions of diophantine equations x^2+pqy^2=z^2, for positive integers x, y, z, and primes p,q. This work is based on the development of the previous results, namely using the solutions of the Diophantine equation x^2+y^2=z^2, and looking at characteristics of the solutions of the Diophantine equation x^2+3y^2=z^2 and x^2+9y^2=z^2.

We construct Riemann Integral for a sequence in a normed space (l^p,‖∙‖_p ). To do construction, we used some theories of real analysis and functional analysis, include some real sequences theories, some Riemann integral theory for functions in R, and some norm theories in a normed space (l^p,‖∙‖_p ). In this paper, we otained that a sequence of functions f=(f_k ):[a,b]⊂R→l^p qualify that the sequence is Riemann integrable on [a,b]⊂R.