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Linear equation

  • Thread starter Gringo123
  • Start date
  • #1
141
0
Have I got this linear equation right?

8y - 31 = 13 - 3y

My answer is y = 8.8
 

Answers and Replies

  • #2
1,171
5
Plug the value you got into the equation and check to see.
 
  • #3
33,503
5,191
Have I got this linear equation right?

8y - 31 = 13 - 3y

My answer is y = 8.8
Your answer is incorrect. Show us how you got your solution and we can steer you in the right direction.
 
  • #4
HallsofIvy
Science Advisor
Homework Helper
41,833
955
Gringo123, I suspect you subtracted 3y from both sides when you should have added it.

But whenever you ask someone to check your answer, you should always show how you got it.
 
  • #5
141
0
Hi Mark. Thanks for helping me out... again!

1st I added 31 to both sides which left me with:
8y = 44 + 3y
From this I could see that 44 = 5y (5y + 3y = 8y)
44 / 5 = 8.8
 
  • #6
24
0
Hi Mark. Thanks for helping me out... again!

1st I added 31 to both sides which left me with:
8y = 44 + 3y
From this I could see that 44 = 5y (5y + 3y = 8y)
44 / 5 = 8.8
It should be "-" not "+".
Why did you change this sign?
 
  • #7
141
0
Once again I've confused everyone with a typo. The original problem is:
8y - 31 = 13 - 3y
I added 31 to both sides:
8y = 44 - 3y
Then I add 3y to both sides:
11y = 44
and I get the right answer, y = 4
Iy was a silly little error on my part. Thanks everyone.
 
  • #8
Mentallic
Homework Helper
3,798
94
It's easier to check for yourself if you have the correct answer or not.

Since you at first found y=8.8, this means if you plug that value in for y in the equation 8y-31=13-3y then you should find that the left-hand side equals the right-hand side. But this isn't true, which means you've made a mistake somewhere. Plugging in y=4 however will make both sides equal, which means you have found the correct value.

This can be for your quadratics as well.
 

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