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How do I solve 4x + 3y=0 & 2x + y = -2 using substitution

User Saskia
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1 Answer

5 votes
4x + 3y = 0
2x + y = -2
take 2x and subtract to the side with -2
it'll look like this: y = -2x - 2
plug that equation in where the y is in the other equation.
it'll look like this: 4x + 3(-2x - 2)=0
which you multiply 3 and the -2x and the -2
which the equation would be: 4x - 6x - 6=0
put together like terms: -2x - 6=0
add the 6 to the side with the zero: -2x = 6
divide both sides by -2 which x= -3
to get y you plug in the answer for x (-3)
2(-3)+y= -2
so it'd then be -6 + y = -2
add the -6 to the side with -2
y= -2 +6
y= 4
so your complete answer is ( -3, 4)
User Benmccallum
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