Question
Function
Find the first partial derivative with respect to u
Find the first partial derivative with respect to r
∂u∂I=r1
Simplify
I=ru
Find the first partial derivative by treating the variable r as a constant and differentiating with respect to u
∂u∂I=∂u∂(ru)
Use differentiation rule ∂x∂(g(x)f(x))=(g(x))2∂x∂(f(x))×g(x)−f(x)×∂x∂(g(x))
∂u∂I=r2∂u∂(u)r−u×∂u∂(r)
Use ∂x∂xn=nxn−1 to find derivative
∂u∂I=r21×r−u×∂u∂(r)
Use ∂x∂(c)=0 to find derivative
∂u∂I=r21×r−u×0
Any expression multiplied by 1 remains the same
∂u∂I=r2r−u×0
Any expression multiplied by 0 equals 0
∂u∂I=r2r−0
Removing 0 doesn't change the value,so remove it from the expression
∂u∂I=r2r
Solution
More Steps

Evaluate
r2r
Use the product rule aman=an−m to simplify the expression
r2−11
Reduce the fraction
r1
∂u∂I=r1
Show Solution

Solve the equation
Solve for r
Solve for u
r=Iu
Evaluate
I=ru
Swap the sides of the equation
ru=I
Cross multiply
u=rI
Simplify the equation
u=Ir
Swap the sides of the equation
Ir=u
Divide both sides
IIr=Iu
Solution
r=Iu
Show Solution
