Derivative of f(x)=1+2p(x-1)+(x-1)^2

  • Thread starter Thread starter UrbanXrisis
  • Start date Start date
  • Tags Tags
    Derivative
AI Thread Summary
The derivative of the function f(x)=1+2p(x-1)+(x-1)^2 is correctly calculated as f'(x)=2p+2(x-1). The confusion arises from misapplying the product rule, as the term 2p(x-1) simplifies to 2p when differentiated, since p is a constant. The derivative of (x-1)^2 contributes an additional 2(x-1), but does not alter the constant nature of p. Thus, the final derivative does not include an extra term as initially suggested. Understanding the application of the product and chain rules is crucial for accurate differentiation.
UrbanXrisis
Messages
1,192
Reaction score
1
p is a real number
f(x)=1+2p(x-1)+(x-1)^2 for x=<1

My book says that the derivative of this function is:
f'(x)=2p+2(x-1)

Shouldnt it be 2p+2(x-1)+2(x-1)

since the derivative of 2p(x-1) is 2p+2(x-1)
and the derivative of (x-1)^2 is 2(x-1)
 
Physics news on Phys.org
p is a real number. It is constant.
 
since the derivative of 2p(x-1) is 2p+2(x-1)

You're misapplying the product rule here.
 
this is what i got

f(x)=1+2p(x-1)+(x-1)^2 for x=<1
f'(x)= 0(x-1) + 2p(1) + 2(x-1)(1)
= 2p + 2(x-1)

use product rule and chain rule
hope that helps...

- Tu
 
Last edited:
the derivitive of 2p(x-1) is:

0(x-1) + 2p(1) which gives u 2p using the product rule

note that p is a constant so when u take the derivitive of it its just a plain 0... sorry i suck at explaining...

- Tu
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top