Question 440075
a. {{{x^2 + 4xy + 4y^2 = (x+2y)^2 = 9}}}
==> x + 2y = 3 (top graph)
 or x+ 2y = -3 (bottom graph)

{{{graph( 300, 300, -5, 5, -5, 5, (3-x)/2, (-x - 3)/2 )}}}

b.  3x + 7y = 8.

{{{graph( 300, 300, -5, 5, -5, 5, (8-3x)/7)}}}