A) 2x -3(3x -7) = 7 . . . . substitute for y
.. -7x = -14 . . . . . . . . . . . subtract 21
.. x = 2 . . . . . . . . . . . . . divide by -7
.. y = 3*2 -7 = -1 . . . . . . substitute for x
(x, y) = (2, -1)
B) 5(5x -2y) -2(3x -5y) = 5(8) -2(1) . . . . subtract 2 times 2nd equation from 5 times 1st
.. 19x = 38 . . . . simplify
.. x = 2 . . . . . . . divide by 19
.. y = (5x -8)/2 = 1 . . . . solve 1st equation for y, substitute x
(x, y) = (2, 1)
C) See the first graph.
(x, y) = (-4, 1)
D) See the second graph.
(x, y) = (3, 2)
