What variation is y=x+2? and also 2x-y=1?

1 Answer
Jun 18, 2018

Both equations are partial variations
Neither is a direct nor an inverse variation.

Explanation:

For a partial variation the value of one variable is:
color(white)("XXX")XXXa constant times the value of the other variable
color(white)("XXX")XXXplus
color(white)("XXX")XXXsome constant value.

Any equation that can be written with variables xx and yy, and constants mm and cc, in the form:
color(white)("XXX")y=mx+cXXXy=mx+c
is a partial variation

(Some definitions of partial variation add the restriction that c!=0c0; that is a partial variation is not also a direct variation).

y=x+2y=x+2 is an obvious partial variation (with m=1m=1 and c=2c=2).

2x-y=12xy=1 can be written as y=2x+1y=2x+1 and is therefore also a partial variation (with m=2m=2 and c=1c=1).