Final Answer:
The expression that represents a quadratic equation in two variables is option B: xy(x^2 - xy + y^2).
Step-by-step explanation:
Definition of a Quadratic Equation in Two Variables:
A quadratic equation in two variables typically has a term involving the square of one or both variables.
Analysis of Each Option:
a) x(1,4x - 3,5y): Not quadratic, no squared terms.
b) xy(x^2 - xy + y^2): Quadratic, contains x^2 and y^2.
c) (1 + 2x - x^2)5x: Not quadratic, no y terms.
d) 3y^2(2y - 1) + y - y(1 - y + y^2) - y^2 + y: Not quadratic, no x^2 terms.
Therefore, the correct expression representing a quadratic equation in two variables is option B: xy(x^2 - xy + y^2).