which expression is a trinomial of degree 1?\n$x^{3}+x^{2}-x$\n$xy^{2}$\n$6 + x - y$\n$3x - y$

Explanation:

Step1: Recall polynomial definitions

A trinomial has 3 terms and degree is highest power of variable.

Step2: Analyze first option

For $x^{3}+x^{2}-x$, highest - power is 3, so degree is 3.

Step3: Analyze second option

$xy^{2}$ has 1 term and degree $1 + 2=3$.

Step4: Analyze third option

For $6 + x-y$, it has 3 terms and highest - power of variables $x$ and $y$ is 1.

Step5: Analyze fourth option

$3x - y$ has 2 terms, so it's not a trinomial.

Answer:

$6 + x-y$