Solution for 12x² -9x less than or equal to 0:
Less than or equal to 0 will be written <=
12x² -9x <= 0 can be also written as follows:
x (12x - 9) <= 0. In order for that expression to be equal to 0 either x has to be <= 0 or 12x - 9 has to be <= 0, so the solution is x <= 0, or 12x - 9 <= 0
In order to solve 12x - 9 = 0 you need to add 9 to both sides of the equation: 12x - 9 + 9 <= 0 + 9:
12x <= 9.
Now divide 9 by 12: x <= 9/12 <= 3/4.