Confused - simple differentiation with simplification

[chuffy]

Homework Statement

differentiate the following
y= x(x+2)(x+3)

Homework Equations

dy/dx

The Attempt at a Solution

The answer I'm given is dy/dx = 2x+5
Would this not be for (x+2)(x+3) = x2 +5x +6
dy/dx = 2x +5 +0

My problem is the x at the beginning of the brackets. Please help!
thanks

 

[NewtonianAlch]

Multiply the equation out and then differentiate, that answer given by the book doesn't seem right.

 

[Curious3141]

Homework Statement

differentiate the following
y= x(x+2)(x+3)

Homework Equations

dy/dx

The Attempt at a Solution

The answer I'm given is dy/dx = 2x+5
Would this not be for (x+2)(x+3) = x2 +5x +6
dy/dx = 2x +5 +0

My problem is the x at the beginning of the brackets. Please help!
thanks

You're right. With the x at the beginning, the final answer is a quadratic expression.

 

[cepheid]

Er...I think I agree actually. Once you multiply through by x, you get x^3 + 5x^2 + 6x.

The derivative of that is not what was given in the answer.

 

[chuffy]

cheers guys I'm going nuts the question states x(x+2)(x+3)
with the answer of 2x+5

 

[NewtonianAlch]

Sometimes, for questions like these, you can simply use an online calculator:

http://www.wolframalpha.com/input/?i=differentiate+y=+x(x+2)(x+3)

Clearly the book is wrong.

 

[chuffy]

thanks for the above link