constant of variation for a direct variation
the nonzero constant k in the function y=kx
direct variation
a linear function defined by an equation of the form y=kx, where k does not equal 0
linear equation
An equation whose graph is a line
opposite reciprocals
A number of the form -b/a, where a/b is a nonzero rational number. The product of a number and its opposite reciprocal is -1.
parallel lines
Two lines in the same plane that never intersect. These lines have the same slope
perpendicular lines
Lines that intersect to form right angles. Two lines are this if the product of their slopes is -1.
point slope form
a linear equation of a nonvertical line written as
y - y1=m(x - x1). The line passes through the point (x1,y1) with slope m.
rate of change
the relationship between two quantities that are changing
slope
the ratio of vertical change to horizontal change
slope-intercept form
the slope-intercept form of a linear equation is y=mx+b, where m is the slope of the line and b is the y-intercept.
standard form of a linear equation
the standard form of a linear equation is Ax+By=C, where A,B, and C are real numbers and A and B are not zero