Question

Solve.

{d+e=2
{d−e=4

Use the substitution method.

There are an infinite number of solutions.

There is no solution.

The solution is (5, 1).

The solution is (3, −1).

Answer 1

From 1st equation
d + e = 2
d = 2 - e

From 2nd equation, subtitute d with 2 - e
d - e = 4
2 - e - e = 4
2 - 2e = 4
-2e = 2
e = -1

Find d
d = 2 - e
d = 2 - (-1)
d = 3

The solution is (3,-1)