i dont understand how this is reached

sandblastedskin

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Nov 18, 2005
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1
im reading a tutorial and they expand :-

2 x (x+1+4) = 20 to become

2 x (x+5) = 20 which i get. but then, using the distributive property(?)
it becomes

2x + 10 = 20

how do they get to that. i cant follow it
 
2x(x+5)=20

2(x^2)+10x=20 ---after ditributeing (2x)

(x^2) + 5x =10 ----after dividing both sides by two

dont know where your answer came from... sure you read it right?

and if you try and solve for x there is no solution that is a real number either, which is not typical result in problems for a beginning algebra course.

it would be correct if your original problem was 2(x+5)=20
where x= Real Number
 
They shouldn't have arrived at that expression for their final answer.

. . . . .2x(x + 5) = 2x(x) + 2x(+5) = 2x<sup>2</sup> + 10x

...not "2x + 10".

Eliz.

Edit: Too fast for me, mammothrob! :wink:
 
ouch!

2(x+5) = 20

They have multiplied both the x and the 5 by 2

2*x + 2 *5 = 20

2x + 10 = 20
 
[Hello, sandblastedskin!

Have you never done any algebra before?

im reading a tutorial and they expand :

2 x (x+1+4) = 20 to become

2 x (x+5) = 20
Did it occur to you that we can't tell an "x" from a "mutliplcation sign" ?

For the sake of other tutors who want to answer
. . he meant: .\(\displaystyle 2\cdot(x\,+\,5)\:=\:20\)
 
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