Question

5. Solve the system:4d + 7e = 68-4d – 6e = -72

Answer 1

4d + 7e = 68

-4d – 6e = -72

We would eliminate d by adding both equations. We have

4d + - 4d + 7e + - 6e = 68 + - 72

4d - 4d + 7e - 6e = 68 - 72

e = - 4

Substituting e = -4 into 4d + 7e = 68, we have

4 * - 4 + 7e = 68

- 16 + 7e = 68

7e = 68 + 16

7e = 84

e = 84/7

e = 12

Thus,

d = - 4, e = 12