How do you solve 3x+4y=2 and x-y+6?

1 Answer
Dean R.
Apr 18, 2018

This is presumably meant to be simple pair of linear simultaneous equations easily solved. The problem is the second one isn't equation; let's guess about what equation was meant:

# 3x + 4 y = 2 #

# x - y = 6 #

Multiplying that equation by #4,#

#4x - 4 y = 24 #

Adding to the first equation,

#7x = 26 #

# x = 26 / 7 #

Multiplying the second equation by three:

# 3x - 3y = 18 #

Subtracting from the first,

# 7y = -16 #

# y = - 16/7 #

Check:

#x-y = 26/7 - -16/7 = 42/7 = 6 \quad \sqrt{}#

#3x + 4y = 1 7 (3(26) + 4(-16)) = 2 \quad \sqrt{}#

Remember we had to guess the equation to start, so this might not be the exact problem the student is trying to answer.

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