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31 votes
31 votes
5m - 2n=4
m - 4n = -1
20 3x + 5y = 11
2x - y=3​

User Nezroy
by
2.9k points

1 Answer

29 votes
29 votes

Answer:

Explanation:

5m - 2n = 4

m - 4n = -1 add 4n to both sides m - 4n + 4n = 4n - 1

m = 4n - 1 now substitute for m into the first equation

5(4n -1) - 2n = 4

20n - 5 - 2n = 4 combine the n coeffients and add 5 to both sides

18n - 5 = 4 + 5

18n = 9 solve for n by dividing 18 by both sides

18 n/18 = 9 /18

n = 1/2 now find for m using m = 4n - 1 m = 4(1/2) - 1 m = 2 -1 = 1

m = 1 (1, 1/2) solves the two equations

3x + 5y = 11 equation 1

2x - y = 3​ multiply both sides by 5 so when you add the two equation

the y term is eliminated (becomes zero)

5(2x-y) = 5(3)

10x - 5y = 15 equation 2 add equation 1 and equation 2

3x + 5y = 11 add the like terms

10x - 5y = 15 add the like terms

(3x + 10x) + (5y - 5y) = (11 + 15)

13x + 0 = 26 the y tern is gone now solve for x

13x = 26

13x/13 = 26/13

x = 2 now find y using 2x - y = 3

2x - y = 3 add y and subtract 3 from both sides

2x - y + (y - 3) = 3 + (y - 3)

2x - 3 = y we already know x = 2

2(2) - 3 = y

4 - 3 = y

1 = y answer (2,1) solves the two equaitons

User Nikitas IO
by
3.1k points
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