Which shape is both a parallelogoram and a rhombus

A square can be defined as a rhombus which is also a rectangle and a parellelogram with four congruent sides and four right angles

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graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.