Solving 2 Chain Rule Problems: Struggling with Derivatives and Need Help

[bblair3]

For some reason I am struggling with these problems. I am lost as a goose trying to fly south for the winter!

Homework Statement

9^(5-x2)
and
another derivative problem using chain rule
r/square root of the whole term r^2+5

Homework Equations

1st equation= d/dx= a^x ln a
2nd equation=

The Attempt at a Solution

1st one= -9^(5-x^2) 2x log (9)

2nd one= i am stuck at square root of (r^2 +5) + square rt (r^2+5) -r^2 all divided by sq root of (r^2+5) all divided by (r^2 +5)^2

any help would be greatly appreciated!

 

[SammyS]

For some reason I am struggling with these problems. I am lost as a goose trying to fly south for the winter!

Homework Statement

9^(5-x^2)

and
another derivative problem using chain rule
r/square root of the whole term r^2+5

Homework Equations

1st equation= d/dx(a^x) = a^x ln a
2nd equation=

The Attempt at a Solution

1st one= -9^(5-x^2) 2x log (9)

2nd one= i am stuck at square root of (r^2 +5) + square rt (r^2+5) -r^2 all divided by sq root of (r^2+5) all divided by (r^2 +5)^2

any help would be greatly appreciated!

1st one looks right.

2nd one: Write using a fractional exponent for square root.

r/(r²+5)^1/2 = r(r²+5)^-1/2. Take the derivative of this.

 

[bblair3]

apparently webassign does not like the answer -9^(5-x^2)2x log (9)

2. 5/(r^2+5)^3/2

 

[bblair3]

the second is right :) thanks...now to figure out what is going on with the first one

 

[SammyS]

Does WebAssign want log or does it want ln for the log base e ?

 

[bblair3]

i will try ln base e

 

[bblair3]

it indeed up being ln
thanks for your help Sammy S :)