Only 25 and 28 are functions.
A function must have only one y value per x value. For 26, the y value of 0 and multiple others have two different y values. For 27, all x values less than 0 have multiple y values.
Number one is 12. There is 12 cubes.
Simplify the equation.
First, distribute the 2 in the left side of the equation.
Resulting in: 2x-6 = (x-1) + 7
Second, remove the parentheses form the right side of the equation (there is nothing to distribute there).
Resulting in: x - 1 + 7
Now simplify the right side of the equation by subtracting the 1 from the 7.
Resulting in: x + 6
Our goal is to isolate the x to the left side, and the numerals to the right side.
With that in mind, add the 6 (from the right side) to both sides. This cancels out the 6 on the right side.
Resulting in: 2x = 12
Lastly, in order to fully isolate the variable (x), we divide both sides by 2.
Resulting in: x = 6
Hope this helps.
