201k views
2 votes
3x − 2y = –17
–x − 9y = –4

User Rich Tier
by
8.1k points

1 Answer

2 votes

Answer: x = -5, y = 1

Explanation:

These are simultaneous equations

I will use the substitution method

BTW [1] means the top equation, and [2] the bottom equation

Rearrange [2] for x

-x = -4 + 9y

x = 4 - 9y

Substitute 4 - 9y into [1]

3(4 - 9y) - 2y = -17

Expand the bracket

12 - 27y - 2y = -17

Simplify

12 - 29y = -17

Rarrange for y

12 = 29y - 17

29y = 12 + 17 = 29

y = 1

Now substitute y into either equation to solve for x

I will use [2] as it looks easier

-x - 9(1) = -4

Expand the bracket

-x -9 = -4

-x = 5

x = -5

Now lets substitute x and y into [1] to check our answer

3(-5) - 2(1) = -17

-15 - 2 = -17

User Suman J
by
7.9k points