noun
indeterminate equation
A mathematical equation with more than one unknown, having infinitely many solutions unless further constraints are given.
不定方程式の解を整数に限定すると、ディオファントス方程式と呼ばれる。
When the solutions of an indeterminate equation are restricted to integers, it is called a Diophantine equation.
方程式 is a general equation; 不定方程式 specifically refers to an indeterminate equation with multiple unknowns and infinite solutions.
A Diophantine equation is a type of indeterminate equation where only integer solutions are sought.
Compound of 不定 (indeterminate) + 方程式 (equation). The term is a direct calque from Western mathematical terminology.