Use the Screen to Solve the Equation or Inequality $y_{1}=f(x)$ Is a Linear Function Defined Over the Domain of Real

Essay

Use the screen to solve the equation or inequality. Here the function $y_{1}=f(x)$ is a linear function defined over the domain of real numbers.
(a) $y_{1}=0$
(b) $y_{1}<0$
(c) $y_{1}>0$
(d) $y_{1} \leq 0$