SOLUTION: Hello, I was asked this question by my teacher but couldn't get the answer, so she asked me to get the answer and how to get there for next class. y = x-12 y=4x She said I coul

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Question 1036645: Hello, I was asked this question by my teacher but couldn't get the answer, so she asked me to get the answer and how to get there for next class.
y = x-12
y=4x
She said I could use elimination or substitution. I decided to use elimination. Please help me.
Found 2 solutions by macston, MathTherapy:
Answer by macston(5194)   (Show Source): You can put this solution on YOUR website!
.
y=x-12
y=4x . Subtract this from above equation to eliminate y.
.
0=-3x-12 . Add 12 to each side
12=-3x . Divide each side by -3.
-4=x
.
y=4x=4(-4)=-16
.
---OR---
.
y=4x
y/4=x . Use this to substitute for x below
.
y=x-12 . Substitute for x from above
y=(y/4)-12 . Subtract (y/4) from each side
(4y/4)-(y/4)=-12
3y/4=-12 . Multiply each side by 4.
3y=-48 . Divide each side by 3.
y=-16
.
y=4x
-16=4x
-4=x
--------
ANSWER x=-4 and y=-16
.
CHECK:
.
y=x-12
-16=-4-12
-16=-16
.
y=4x
-16=4(-4)
-16=-16
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

Hello, I was asked this question by my teacher but couldn't get the answer, so she asked me to get the answer and how to get there for next class.
y = x-12
y=4x
She said I could use elimination or substitution. I decided to use elimination. Please help me.
Why would you ant to use elimination? Don't you want to use the EASIER method of the 2?

y = x - 12 ------ eq (i)

y = 4x -------- eq (ii)

Both equations are already solved for y, so choosing one of the values of y, and substituting that value into the other equation will work fine

4x = x - 12 ------- Substituting 4x for y in eq (i)

4x - x = - 12

3x = - 12

 



y = 4(- 4) ----- Substituting - 4 for x in eq (ii)





Don't make things harder for yourself! Choose the easier/est way out! 

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