# Which of the following is the equation for all straight-line equation?

# 1) y = 4x^{2} 2) x = 9y^{2 } 3) x^{2} + y^{2} = 9 4) y = 4x + 9

A straight line equation is a homogenous, single degree equation of two variables.

## Answer: Option (4) y = 4x + 9 matches with the above definition, and is the required equation of the line.

Go through the explanation to understand better.

**Explanation:**

The standard equation of a straight line is y = m x + c

Here, m gives the slope of the line and c gives the value of the y-intercept.

In the given options, y = 4x + 9 is the only equation which of the form y = m x + c.