Answer
The error that the student made was they did not multiply the last part of the second equation, which is -3, by 4. This is what resulted in the incorrect answer.
The first equation should be solved like this:
1st : $5x+4y = 2$ then multiplied by 3 to get $15x+12y = 6$
The second equation should be solved like this:
2nd: $3x+3y = -3$ then multiplied by 4 to get $12x+12y= -12 $
These equations should then be subtracted (the 1st - 2nd)
to get $3x= -6$.
Dividing both sides by 3 will get the value of $x=-2$. This is the correct solution to this system.
Work Step by Step
See above.
