Which of the following is the equation for all straight-line equation?
(1) y = 4x²  (2) x = 9y²  (3) x² + y² = 9  (4) y = 4x + 9

Solution:

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

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.

Thus, only option (4), y = 4x + 9 matches with the above definition, and is the required equation of the line.

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

Summary:

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