Solving for X am I working this right

oasuspender

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Sep 27, 2009
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5x-(2x+2)=x+(3x-5)
3x-2=4x-5
taking 4 x from right from left too
-1x-2=-5
adding 2 to each side
x= -3 correct?


Trying to learn this stuff want a proof check
 
5x-(2x+2)=x+(3x-5)
3x-2=4x-5

At this point, you should collect all the x terms on one side, and all the constants on the other.

3x - 2 = 4x - 5
3x - 4x = 2 - 5
-x = -3
x = 3

To see if x = 3 is correct:

Left Side:
5(3) - [2(3) + 2] = 15 - 8 = 7

Right Side:
3 + [3(3) - 5] = 3 + 4 = 7
 
oasuspender said:
… 3x - 2 = 4x - 5

taking 4x from right from left too

-1x - 2 = -5

adding 2 to each side You're correct, up to this point.

x = -3 correct? … NO. Why did you change -1x to x ?

… want a proof check Check by substituting your candidate(s) for solution into the original equation and simplify to see if you end up with a true statement.


Your work is fine; you just dropped a negative sign.

BTW, when a coefficient is -1, we don't write -1. We only write the negative sign.

In other words, don't write -1x; write -x, instead.

After fixing your dropped negative sign, we have the following corrected result.

-x = -3

Can you finish? 8-)

Here's how the check would go, with your previous candidate for solution: x = -3

We substitute -3 for x everywhere x appears in the original equation.

5[-3] - (2[-3] + 2) = [-3] + (3[-3] - 5)

Now simplify each side.

-15 - (-6 + 2) = -3 + (-9 - 5)

-15 - (-4) = -3 + (-14)

-15 + 4 = -3 - 14

-11 = -17

The result is not a true statement; therefore, -3 is not a solution.

 
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