MHB Why Is My Solution 9x+-11 Incorrect for the Algebra Problem -6(x+2)+10+3(x-3)?

[Calista A]

this is a problem that i am working on -6(x+2)+10+3(x-3) in which i got the answer of 9x+-11 and apparently i am wrong, can someone help me understand this more.

 

[skeeter]

$-6(x+2) + 10 + 3(x-3) = -6x - 12 + 10 + 3x - 9$

now, combine like terms

 

[Calista A]

$-6(x+2) + 10 + 3(x-3) = -6x - 12 + 10 + 3x - 9$

now, combine like terms

i added -6x to 3x and got 9x so now i have 9x-12+10 - 9 is this correct?

 

[romsek]

i added -6x to 3x and got 9x so now i have 9x-12+10 - 9 is this correct?

you can combine the numbers,

$$-12+10-9$$

as well

 

[Prove It]

i added -6x to 3x and got 9x so now i have 9x-12+10 - 9 is this correct?

-6x + 3x is not 9x, it's -3x.

 

[Calista A]

-6x + 3x is not 9x, it's -3x.

why... this is what i was stuck on, i thought you add on both sides which is why i was getting 9x

 

[skeeter]

what “both sides” ?
what you posted is a single expression, not an equation.

The sum of two terms in an expression with opposite signs is the difference between the two terms, and keeping the sign of the greater term.

 

[topsquark]

why... this is what i was stuck on, i thought you add on both sides which is why i was getting 9x

How did you get -12 + 10 - 9 = -11 but not -6x + 3x = (-6 + 3)x = -3x? The addition of numbers works the same way!

-Dan

 

[HOI]

this is a problem that i am working on -6(x+2)+10+3(x-3) in which i got the answer of 9x+-11 and apparently i am wrong, can someone help me understand this more.

First "+-11" is not a number and makes no sense.
-6(x+ 2)= -6x- 12
3(x- 3)= 3x- 9

Together they add to (-6+ 3)x- 12- 9= -3x- 21

Adding 10 to that: -3x- 11.