What is the most efficient first step to isolate the variable term on one side of this equation? -9x = -4x + 5 a. subtract 5 from both sides. b. add 5 to both sides. c. subtract 9x from both sides. d. add 4x to both sides.

For this case we have the following equation:

We want to clear x:

For this we must follow a series of steps, the first consists of adding 4x to both sides of the equation to obtain:

In this way, the variable term remains on one side of the equation.

Thus, the first step will be:

Add 4x to both sides

Option D

Answer

D. Add 4x to both sides.

Explanation

-9x = -4x + 5

On the right hand side we have -4x. We have to add 4x on both sides to have;

-9x + 4x= -4x + 5 + 4x          

(-4x + 4x = 0)

(-9x + 4x = -5x)

∴ -5x = 5