-3x - 6(x-4) = 9

[jwk811]

I Don't know how I am getting this wrong. ........
-3x - 6(x-4) = 9
-3x - 6x - 24 = 9
-9x - 24 = 9
+24 + 24
-9x = 33
/3 /3
-3x = 11
x = -11/3


The answer in the book is 5/3
How are they getting this?


Another question: Can I multiply -6 to x and -4 (instead of [-3x -] [6x-24] make it -3x(-6x+24)? I don't think you can but could someone clarify that for me?


THANKS!!!!!!

 

[Deleted member 4993]

I Don't know how I am getting this wrong. ........
-3x - 6(x-4) = 9
-3x - 6x - 24 = 9 → Right here .... it should be

- 3x - 6x + 24 = 9

-9x + 24 = 9

-9x + 24 - 24 = 9 -24

- 9x = -15

x = (-15)/(-9)

x = 5/3

-9x - 24 = 9
+24 + 24
-9x = 33
/3 /3
-3x = 11
x = -11/3


The answer in the book is 5/3
How are they getting this?


Another question: Can I multiply -6 to x and -4 (instead of [-3x -] [6x-24] make it -3x(-6x+24)? Nope - you cannot do that!!

I don't think you can but could someone clarify that for me?


THANKS!!!!!!

.

 

[JeffM]

I Don't know how I am getting this wrong. ........
-3x - 6(x-4) = 9
-3x - 6x - 24 = 9 ERROR here.
-9x - 24 = 9
+24 + 24
-9x = 33
/3 /3
-3x = 11
x = -11/3


The answer in the book is 5/3
How are they getting this?


Another question: Can I multiply -6 to x and -4 (instead of [-3x -] [6x-24] make it -3x(-6x+24)? I don't think you can but could someone clarify that for me?


THANKS!!!!!!

Thank you for showing your work.

Step by painful step.

\(\displaystyle -3x - 6(x - 4) = 9 \implies\)

\(\displaystyle -3x + (-6)(x - 4) = 9\implies\)

\(\displaystyle -3x - 6x + (-6)(- 4) = 9\implies\)

\(\displaystyle -3x - 6x + 24 = 9\implies\)

\(\displaystyle -3x - 6x + 24 - 24 = 9 - 24\implies\)

\(\displaystyle -3x - 6x = 9 - 24 = - 15\implies\)

\(\displaystyle - 9x = - 15 \implies\)

\(\displaystyle \dfrac{-9x}{-9} = \dfrac{-15}{- 9} \implies\)

\(\displaystyle x = \dfrac{5}{3}.\)

 

[jwk811]

thanks! so i guess you multiple by -6 instead of 6..... thats confusing ;-)

 

[JeffM]

thanks! so i guess you multiple by -6 instead of 6..... thats confusing ;-)

\(\displaystyle - (+ 6)(- 4) = - (- 24) = + 24.\)

\(\displaystyle + (- 6)( - 4) = + (+ 24) = + 24.\)

Two ways to think about it: same result.