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Mathematics 8 Online
PuppyFlower:

Help again .-. This stuff confuses me. https://prnt.sc/faydfy I think its no solution My work below -3 : 3/3(-3) + 1/-3+4 = 10/7(-3) 3/-9 + 1/1 = 10/-21 4/-8 = 10/-21 3: 3/3(3) + 1/3+4 = 10/7(3) 3/9 + 1/7 = 10/-21 4/16=10/21 -3,3 : 3/3(-3) + 1/-3+4 = 10/7(3) 3/-9 + 1/1 = 10/21 4/8 = 10/21

Nnesha:

It would be much easier if we just solve for the variable.

Hero:

@PuppyFlower, do you think you might be able to hit that equation button and type out your work?

Nnesha:

3: 3/3(3) + 1/3+4 = 10/7(3) ( we can reduce 3/9 to 1/3) 3/9 + 1/7 = `10/-21` ( 3 is positive ) 4/16=10/21 1/3+1/7=?

Hero:

Doing so creates nice equations like this: \(\dfrac{3}{3x} + \dfrac{1}{x + 4} = \dfrac{10}{7x}\)

Nnesha:

For 3rd option: x=-3 , x=3 means both are solution if you plug in the x value one at a time\[\rm (for~x=-3)~\rightarrow ~\frac{ 3 }{ 3(\color{Red}{-3}) } +\frac{1}{\color{red}{-3}+4} = \frac{10}{7(\color{Red}{-3})}\] \[\rm (for~x=3)~\rightarrow ~\frac{ 3 }{ 3(\color{Red}{3}) } +\frac{1}{\color{red}{3}+4} = \frac{10}{7(\color{Red}{3})}\]

Nnesha:

in other words.. IF you replace the variable x with 3 on left side then you have to replace the variable x with the same number 3 on the right side.

PuppyFlower:

I know, I just get confused at the end when I have to pick an answer then I don't understand it

PuppyFlower:

OH, I get it now lol, you don't use both -3 and 3 in the same equation, if they both give you the right answer then it would be both

Hero:

It's better to assume they did not give you the correct variables and just do the following: \(\dfrac{3}{3x} + \dfrac{1}{x + 4} = \dfrac{10}{7x}\) \(\dfrac{1}{x} + \dfrac{1}{x + 4} = \dfrac{10}{7x}\) \(\dfrac{7}{7x} + \dfrac{1}{x + 4} = \dfrac{10}{7x}\) \(\dfrac{1}{x + 4} = \dfrac{10}{7x} - \dfrac{7}{7x}\) \(\dfrac{1}{x + 4} = \dfrac{10 - 7}{7x}\) \(\dfrac{1}{x + 4} = \dfrac{3}{7x}\) Cross Multiply to get: \(7x = 3(x + 4)\) Then distribute to get \(7x = 3x + 12\) Then put like terms on the same side to get: \(7x - 3x = 12\) Then simplify to get: \(4x = 12\) Then divide both sides by 4 to isolate \(x\)

PuppyFlower:

I'm sorry but you just made everything harder for me. I'm guessing the answer is both.

Hero:

The answer is NOT both

Nnesha:

the way you were trying to find the answer is harder/tedious than solving for the variable.

Nnesha:

I'm not saying it's wrong.

Hero:

I'm not a fan of these multiple choice questions. It only encourages the student to do things the wrong way.

Nnesha:

yeah especially not for math. I remember when I Used to solve each question step by step on the final exam. No multiple choice questions...not even for bio/chem/phy exams.

Nnesha:

3/3(-3) + 1/-3+4 = 10/7(-3) `3/-9 + 1/1` = 10/-21 4/-8 = 10/-21 \[-\frac{ 3 }{ 9 } +1=-\frac{10}{21}\] 3/9=1/3 \[-\frac{1 }{ 3 } +1=-\frac{10}{21}\] (-1/3)+1 isn't equal to -4/8

Nnesha:

`3/3(3) + 1/3+4 = 10/7(3) 3/9 + 1/7 = 10/-21 4/16=10/21` same mistake here 1/3+1/7 isn't equal to 4/16

Nnesha:

` 3/3(3) + 1/3+4 = 10/7(3)` `3/9 + 1/7 = 10/-21` `4/16=10/21 ` same mistake here 1/3+1/7 isn't equal to 4/16

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