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18 votes
18 votes
Solve by substituton

Solve by substituton-example-1
User Neeraj Mehta
by
2.1k points

2 Answers

22 votes
22 votes

Solve the first equation for
x.


x+3y = -2 \implies x = -3y - 2

Substitute this into the second equation and solve for
y.


-3(-3y-2) + y = 6 \implies 9y + 6 + y = 6 \implies 10y = 0 \implies y=0

Now solve for the value of
x.


x = -3\cdot0 - 2 = -2

So the solution to the system is the point
(x,y) = \boxed{(-2,0)}

User Evan Benn
by
3.0k points
11 votes
11 votes

Answer:


\left( \: \boxed{-2}\:, \: \boxed{0} \: \right)

Explanation:

Given system of equations:


\begin{cases}x+3y=-2\\-3x+y=6 \end{cases}

To solve using the method of substitution, solve one equation for one of the variables.

Solving equation 2 for y:


\implies -3x+y=6


\implies -3x+y+3x=3x+6


\implies y=3x+6

Substitute this expression into the other equation and solve for x:


\implies x+3y=-2


\implies x+3(3x+6)=-2


\implies x+9x+18=-2


\implies 10x+18=-2


\implies 10x+18-18=-2-18


\implies 10x=-20


\implies 10x / 10=-20 / 10


\implies x=-2

Substitute the found value of x into the expression for y, and solve for y:


\implies y=3x+6


\implies y=3(-2)+6


\implies y=-6+6


\implies y=0

Therefore, the solution to the given system of equations is:


\left( \: \boxed{-2}\:, \: \boxed{0} \: \right)

User Ololoepepe
by
2.9k points