Dependent variables: A variable whose value depends on the value of another variable or variables
independent variable: A variable whose value determines the value of another variable or variables
Cos -2x or -cos2x, it's the difference.
To help you understand this, it is helpful to create a sample set of data:
__,__,__,(Q1 is here)__,__,__,(median is here)__, __,__,(Q3is here)__,__,__
A. The first 3 lines are 3 pieces of data in the first quartile.
B. here are 6 pieces of data between the 1st and 3rd quartiles.
D. There are 3 pieces of data in the upper quartile.
(1.5 + x) / 2 = 2 .... multiply both sides by 2
1.5 + x = 2 * 2
1.5 + x = 4
x = 4 - 1.5
x = 2.5 meters per second