Math Is Fun Forum

Mathando

Member

Registered: 2018-06-20

Posts: 3

Please help explain math expansion

Could someone help explain the expansion below:
Square(x+Δx) -> square(x)+ 2x Δx + square(Δx)

In my understanding, below should be the correct expansion:
Square(x+Δx) -> square(x) + square(Δx)

My question is from reading “introduction to derivative” article on MathIsFun

Thanks,

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,855

Re: Please help explain math expansion

Hi Mathando,

Introduction to Derivative.

The slope formula is:    

Put in

and

.
Simplify

and

cancel

Simplify more (divide through by Δx):    = 2x + Δx
Then as Δx heads towards 0 we get:    = 2x

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

Mathando

Member

Registered: 2018-06-20

Posts: 3

Re: Please help explain math expansion

http://www.mathisfunforum.com/latex/b/1/4e18c1f224b02b22693d61ffad4eff1.gif

Could you elaborate about more. Where does 2x delta x come from ?

Thanks

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,855

Re: Please help explain math expansion

Hi,

.

---

It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

Mathando

Member

Registered: 2018-06-20

Posts: 3

Re: Please help explain math expansion

Thanks