Question

Solve, using the substitution method.

y – 3x = 7
21 9x = 3y

a.
there is no solution.

b.
there are an infinite number of solutions.

c.
the solution is (1, 10)

d.
the solution is (28, 0)

Answer 1

y - 3x = 7 . . . . . . . . (1)
21 + 9x = 3y . . . . . .(2)
From (1), y = 3x + 7
substituting for y into (2), we have
21 + 9x = 3(3x + 7) = 9x + 21
0 = 0
Therefore, the system has an infinte number of solutions.