# Express algebraically

• Nov 19th 2009, 08:40 AM
reiward
Express algebraically
Express each of the following algebraically:

a. a vertical line 2 units to the left of the y-axis
b. a line parallel to the x-axis and contains the point (3,5)
c. a set of points where the abscissa is always twice the ordinate.
d. the set of pints in the fourth quadrant

• Nov 19th 2009, 09:00 AM
ukorov
Quote:

Originally Posted by reiward
Express each of the following algebraically:

a. a vertical line 2 units to the left of the y-axis
b. a line parallel to the x-axis and contains the point (3,5)
c. a set of points where the abscissa is always twice the ordinate.
d. the set of pints in the fourth quadrant

a. x = -2
b. y = 5
c. $\displaystyle y = \frac{x}{2}$ + c (c = constant)
d. ......(x, -y)...?
• Nov 19th 2009, 09:08 AM
metlx
a) x = -2

b) a line that is parallel to x axis and goes through (3,5) also goes through (4,5) and (5,5).. etc. any x is good as long as y coordinate remains 5.

so y = 5
covers them all x-es.

c)
abscissa = x-axis
ordinate = y-axis

x = 2y
or better
y = x/2

d) 4th quadrant is the lower right one.
in the 4th quadrant x are positive and y are negative.
so x > 0
and y < 0.
M = {x,y | (x>0) ^ (y<0)}