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Show and explain how replacing one equation by the sum of that equation and a multiple of the other produces a system with the same solutions as the one shown. 8x + 7y = 39 4x – 14y = –68

User StvnW
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2 Answers

4 votes

Answer:

(1/2, 5)

Explanation:

8x + 7y = 39

-2(4x - 14y = -68)

-8x + 28y = 136

8x + 7y = 39

add the two equations together

35y = 175

y = 5

8x + 7(5) = 39

8x = 4

x = 1/2

User Acewin
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4.2k points
7 votes

Answer:

Using the linear combination method, you can multiply the first equation by 2 and add the equations to get 20x = 10. Dividing both sides by 20, x = 1/2. To solve for y, substitute 1/2 for x in the equation 8x + 7y = 39 to get 4 + 7y = 39. Solving this equation, y = 5. Checking this in the other equation, 4(1/2) – 14(5) = –68 results in 2 – 70 = –68 or –68 = –68. The solution of the system shown is (1/2, 5). The system 8x + 7y = 39 and 20x = 10 is formed by replacing 4x –14y = –68 by a sum of it and a multiple of 8x + 7y = 39. Since 20(1/2) = 10, the system 8x + 7y = 39 and 20x = 10 also has a solution of (1/2, 5).

Explanation:

exactly from EDGE 2020

User Dhiraj Wakchaure
by
4.6k points