# Derivative help (1 Viewer)

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#### schlynn

1. The problem statement, all variables and given/known data
Ok, im learning about derivative's, and they seem to elude me for some reason. I have this.

x2+x

I know the derivative is 5, and the function is differentiable at 2. But I don't understand how you get it. I know the limit you use to find it, but the shortcut is nxn-1 right? Where does n come from? And x=2 right? Would it be 2*21? But thats not 5, its 4. What am I doing wrong? Please, detailed answers are very very appreciated.

2. Relevant equations
Pretty sure that I noted all the nessicary equations above.

3. The attempt at a solution
I said what I attempted above.

#### Duncan1382

1. The problem statement, all variables and given/known data
Ok, im learning about derivative's, and they seem to elude me for some reason. I have this.

x2+x

I know the derivative is 5, and the function is differentiable at 2. But I don't understand how you get it. I know the limit you use to find it, but the shortcut is nxn-1 right? Where does n come from? And x=2 right? Would it be 2*21? But thats not 5, its 4. What am I doing wrong? Please, detailed answers are very very appreciated.

2. Relevant equations
Pretty sure that I noted all the nessicary equations above.

3. The attempt at a solution
I said what I attempted above.
You've just got to learn the rules of derivatives.

The derivative is:

f(x) = 2x + 1

for the first one, pull out the exponent and make it a coefficient while lowering the exponent by 1 degree. Same thing for the second term.

#### bns1201

The original function x^2+x can be seen as x^2+x^1

n is the exponent for each x, so for the first x, n=2 and n=1 for the second x

then use the derivative formula which is dy/dk of f(x) = nx^(n-1)

which would mean the derivative is 2x^(2-1)+1x^(1-1) which equates to 2x^2+1

since it asks what the value of dy/dx is at x=2, you plug 2 into the derivative for an answer of 2(2)+1 which equals 5

#### schlynn

Thank you so much.

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