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Solve the system by substitution. y=-3, -3x-5y=6

User Xiamx
by
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2 Answers

12 votes
If we have the substitution for y, replace the y in the equation with -3
-3x-5(-3)=6
Multiply the -5 with the -3, and when you multiply a negative number with a negative it turns into a positive
-3x+15=6
Bring the 15 over to the other side of the equation to get the x number by itself like this —-> -3x=6-15 and when you cross over a number to the other side of the equation it’s positive or negative sign changes into the opposite
Now subtract
-3x=-9
Divide
-3x = -9
—— ——
-3 -3
And a negative number divided by a negative also makes the number a positive
X=3
User Rushikesh Thakkar
by
4.6k points
6 votes

Answer:

x=3

Explanation:

-3x-5y=6

-5 times -3 = 15

-3x+15=6

+3x on both sides

15=6+3x

-6 on both sides

9=3x

divide by 3 on both sides

x=3

User Ajay Thakur
by
4.6k points