Solving Multi-Step Equations: 21 = 6 - x - 4x

[math87690]

I have a question, here is the problem 21=6-x-4x. And then I need to know how to check the answer. I would like you to reply as soon as possible please. I thank you for your help to. And when you reply could you tell me how long it regularly takes to reply.

 

[jonboy]

Hello, math87690!

So many variable I can't tell you how long it take to reply.

You can check your answer by filling what you found $\displaystyle x$ to be and see if the equation is balanced (same number on both side of the equations).

So with that being said:

\(\displaystyle \L \;21\,=\,6\,-x\,-4x\)


Combine like terms: \(\displaystyle \L \;21\,=\,6\,-5x\)


Subtract 6: \(\displaystyle \L \;15\,=\,-5x\)


Divide by -5: \(\displaystyle \L \;-3\,=\,x\)


...........Transitive Property: \(\displaystyle \L \;x\,=\,-3\)

Now you fill $\displaystyle x$ back in our original equation ($\displaystyle 21\,=\,6\,-x\,-4x$) and see if it is balanced.

 

[Denis]

I have a question, here is the problem 21=6-x-4x.

Keep it simple :shock:
Add 5x to both sides:
5x + 21 = 6
Subtract 21 from each sides:
5x = -15
Divide each side by 5:
x = -3

 

[sgtpepper]

here's the proof it worked

here's the proof it worked: I assigned -3 for x then plugged in the right hand side of the equation which, with x equivalent to -3, should equal 21 (the left side of the equation)