Question #b310b

1 Answer
sente
Oct 9, 2016

#(x, y) = (x, x-90)#

Explanation:

Given two variables, at least two equations are needed to determine two unique values for those variables. With only a single equation, we are showing a relationship between the two variables which may be fulfilled by many #(x, y)# pairs.

In the given example, we have #x-y = 90#

#=> x - y + y - 90 = 90 + y - 90#

#=> y = x - 90#

Thus, for any #x# value, we can find a corresponding #y# value which fulfills #x-y=90# by setting #y=x-90#. If we graph this, we get a line, every point of which is an #(x, y)# pair satisfying our equation:

graph{x-90 [-275, 333, -168, 136]}

Example #(x,y)# pairs:
#(-10, -100)#
#(0, -90)#
#(1, -89)#
#(10, -80)#
#(90, 0)#
#(100, 10)#

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