Question

How do you solve - 5d + 8e =-21
3d - 4e = 15 with system of equations

Answer 1

d = 9

e = 3

Explanation:

- 5d + 8e =-21

3d - 4e = 15 | ×2

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- 5d + 6d + 8e - 8e = - 21 + 30

d = 9

3d - 4e = 15

3×9 - 4e = 15

4e = 27 - 15

4e = 12

e = 3

Answer 2

d = 9, e = 3

Explanation:

Given the 2 equations

- 5d + 8e = - 21 → (1)

3d - 4e = 15 → (2)

Multiplying (2) by 2 and adding to (1) will eliminate the term in e

6d - 8e = 30 → (3)

Add (1) and (3) term by term to eliminate e, that is

d = 9

Substitute d = 9 into either of the 2 equations and solve for e

Substituting into (2)

3(9) - 4e = 15

27 - 4e = 15 ( subtract 27 from both sides )

- 4e = - 12 ( divide both sides by - 4 )

e = 3

Thus d = 9 and e = 3