This Linear Equation Answer Can't be Correct

• Nov 5th 2012, 02:49 AM
MathClown
This Linear Equation Answer Can't be Correct
Linear Equation: 7x+5/3=11 Answer: x=4/3 ... I'm not getting that answer and don't know in which step I went wrong.

Can someone expand and this and show me how the solution was derived. Thank you!
• Nov 5th 2012, 03:00 AM
a tutor
Re: This Linear Equation Answer Can't be Correct
Multiply through by 3.

21x+5=33

Can you do it from there?
• Nov 5th 2012, 03:11 AM
Petrus
Re: This Linear Equation Answer Can't be Correct
You can also do like this
take away 5/3 on both side then you got
7x=11-5/3
can u finish this?
• Nov 5th 2012, 03:45 AM
Petrus
Re: This Linear Equation Answer Can't be Correct
can you show me your progress so i can say what u did wrong :)? its better if i help you with your progress
• Nov 5th 2012, 03:59 AM
MathClown
Re: This Linear Equation Answer Can't be Correct
Quote:

Originally Posted by Petrus
can you show me your progress so i can say what u did wrong :)? its better if i help you with your progress

I'm struggling with 9th grade math :-(

But here's how I did it: 3+5*7x/3=11

3+35x/3=11

3+35x=3*11

3+35x=33

-3 3+35x=33 -3

35x = 30

x = 35/30...

I don't understand the sequence of numbers you have to either add or multiply when solving the equation. How do I know what to multiply with such equations?
• Nov 5th 2012, 04:07 AM
Petrus
Re: This Linear Equation Answer Can't be Correct
the misstake u do is that u cant multiplicate 7x with 5 :P your method seems like a tutor its simple look at his tips!:)
dw i also sometimes struggle with 9th grade mat :D
• Nov 5th 2012, 04:58 AM
skeeter
Re: This Linear Equation Answer Can't be Correct
Quote:

Originally Posted by MathClown
Linear Equation: 7x+5/3=11 Answer: x=4/3 ... I'm not getting that answer and don't know in which step I went wrong.

Can someone expand and this and show me how the solution was derived. Thank you!

first off, is the equation

$\frac{7x+5}{3} = 11$

or

$7x + \frac{5}{3} = 11$

???
• Nov 5th 2012, 05:36 AM
MathClown
Re: This Linear Equation Answer Can't be Correct
Quote:

Originally Posted by skeeter
first off, is the equation

$\frac{7x+5}{3} = 11$

or

$7x + \frac{5}{3} = 11$

???

The equation is the FIRST one you posted. Sorry for the ambiguity. Can you lend me hand with it?
• Nov 5th 2012, 05:40 AM
Petrus
Re: This Linear Equation Answer Can't be Correct
if the equation is
$\frac{7x+5}{3} = 11$
then that x=4/3 is wrong answer
if we multiplicate with 3 then we get
$\frac{7x+5}{1} = 33$ (why i got divide by 1 is because im not good with that latex code.. it get strange if i take away 1 but you understand)
can you finish this?
• Nov 5th 2012, 05:42 AM
richard1234
Re: This Linear Equation Answer Can't be Correct
Quote:

Originally Posted by MathClown
The equation is the FIRST one you posted. Sorry for the ambiguity. Can you lend me hand with it?

x = 4/3 is the correct answer for the second equation. Not the first one...something's wrong here.
• Nov 5th 2012, 05:49 AM
skeeter
Re: This Linear Equation Answer Can't be Correct
Quote:

Originally Posted by MathClown
The equation is the FIRST one you posted. Sorry for the ambiguity.

next time use grouping symbols to make your equation clear to those who read it ...

Quote:

Linear Equation: (7x+5)/3=11
$\frac{7x+5}{3} = 11$

multiply both sides by 3 to clear the fraction ...

$7x+5 = 33$

subtract 5 from both sides ...

$7x = 28$

divide both sides by 7 ...

$x = 4$

substitute your solution back into the original equation to check ...

$\frac{7(4)+5}{3} = \frac{28+5}{3} = \frac{33}{3} = 11$