math problem

[CpharmAH1]

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I don't get the rigth answer for this problem, do you know how to do it?

If F(x) = ( 2x + 1 )^6 , then F' (-1) =???

 

[nerv12345]

uhhh...i SUCK at calculus but i'm going to guess the answer is -12?

find the derivative of the outside function multiplied by the derivative of the inside function (isn't this the chain rule?)


( 2x + 1 )^6

6(2x+1)^5 multiplied by (2)

plug in -1 into X and the answer comes out to be -12

 

[CpharmAH1]

yeah that's the answer, the problem is that i need to take calculus, i'm missing that class.thanks😀

 

[think]

i thought it was -12^5 😕?

 

[fenixtnlfan]

i thought it was -12^5 😕?

No. You plug in -1 where x is so:

6(2)[(2(-1)+1]^5=12(-1)^5. Only the -1 has the exponent. Hope that helps.

 

[JohnKimx83]

uhhh...i SUCK at calculus but i'm going to guess the answer is -12?

find the derivative of the outside function multiplied by the derivative of the inside function (isn't this the chain rule?)


( 2x + 1 )^6

6(2x+1)^5 multiplied by (2)

plug in -1 into X and the answer comes out to be -12

Why is it multiplied by (2)?

 

[TheRxQueen]

Because 2 is the derivative of (2X + 1).
As nerv12345 points out, chain rule is basically derivative of the outside function times the derivative of the inside function. (2X+1) is the inside function.