2021. Transform the Multivariate to Unitevariate System and Using Elimination and Duplication Matrices with Some Applications. Journal of Al-Rafidain University College For Sciences ( Print ISSN: 1681-6870 ,Online ISSN: 2790-2293 ). 30, 2 (Oct. 2021), 35–47. DOI:https://doi.org/10.55562/jrucs.v30i2.364.