Consider the equation of a straight line of the form, b=ma + e
Where, m>0 is called the slope of the straight line, e>0 is called the intercept on the vertical axis. When ‘a’ increases by 1 unit, the value ‘b’ increases by ‘m’ units. These are called movements of variables along the line. The entity ‘e’ is called the parameter of the line.
As the value of m increases, the straight line swings upward, This is called a parametric shift of line.
(i) A positively sipping straight line swings or rotates downward as its slope decreases.
(ii) A positively sloping straight line shifts upward parallel when its intercept increases.