Working out of this algebra equation?

👨🏻‍🏫 學術台 數學
2009-03-11 9:02 am
Could anyone please show me an easy way to solve an equation like this?

5( x - 3) - 4 ( x + 8 ) = 2x

I'm really stuck with this one :S
the answer is supposed to be negative 47.

Thanks (:
更新1:

btw the aim is to figure out what x is.

回答 (9)

2009-03-11 9:12 am
✔ 最佳答案
1. Expand the brackets.

So you will now have ...

5x - 15 - 4x - 32 = 2x

2. Collect like terms.

x - 47 = 2x

3. Bring the 2x to the left side of the equation

x - 2x - 47 = 0
-x - 47 = 0

4. Add 47 to both sides of the equation.

-x = 47

5. Divide both side by negative 1

x = - 47
👍 0 👎 0
2009-03-11 9:06 am
5( x - 3) - 4 ( x + 8 ) = 2x
5x - 15 - 4x - 32 = 2x
5x - 4x - 15 - 32 = 2x
x - 47 = 2x
-47 = 2x - x
-47 = x
x = - 47
👍 1 👎 0
2009-03-11 12:03 pm
5(x - 3) - 4(x + 8) = 2x
5*x - 5*3 - 4*x - 4*8 = 2x
5x - 15 - 4x - 32 = 2x
5x - 4x - 2x = 15 + 32
-x = 47
x = 47/-1
x = -47
👍 0 👎 0
2009-03-11 9:19 am
5( x - 3) - 4 ( x + 8 ) = 2x
5x-15-4x-32=2x
5x-4x-2x=32+15
-x=47
x=-47 answer//
👍 0 👎 0
2009-03-11 9:16 am
5x - 15 - 4x - 32 = 2x
5x - 15 - 4x - 32 - 2x = 0
- x - 47 = 0
-x = 47
x = -47
👍 0 👎 0
2009-03-11 9:13 am
5( x − 3) − 4 ( x + 8 ) = 2x
or 5x−15−4x−32= 2x
or 5x−4x − 15 −32 =2x
or x−47 = 2x
or x−2x = 47
−x= 47
or x = − 47
👍 0 👎 0
2009-03-11 9:10 am
So you multiply into the brackets:

(5x-15)-(4x+32)=2x

You work the negative into the second bracket:

5x-15-4x-32=2x

And you do the simple math:

5x-4x = x
-15-32 = -47

so

x-47 = 2x
-47 = x
👍 0 👎 0
2009-03-11 9:07 am
expand

5x - 15 -4x - 32 = 2x
minus 2x from both sides

-x - 47 = 0
plus x on both sides

-47 = x
👍 0 👎 0
2009-03-11 9:08 am
lawls i might have gotten it wrong but oh wells

5( x - 3) - 4 ( x + 8 ) = 2x; equation
5x - 15 - 4x - 32 = 2x; contributive property
x - 15 - 32; combine like terms
x - 47 = 2x; subtract x from both sides
x=-47; lawls
參考: heh.
👍 0 👎 1


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