Differentiation - Chain Rule

Could someone pls explain how I can solve these differentiation questions using the chain rule.

1. y = (1+(1+x^2)^5)^4

2. y = (1/(3x^2+1)^1/2)^3

Well so far I have tried subsitute the inside bracket for u and then differentiate. For the first question I got: 20(1+x^2)^4(1+(1+x^2)^3)^310(1+x^2)^4
But this is wrong, the answers say it is: 40x(1+(1+x^2)^5)^3(1+x^2)^4

For the second question I tried the same thing. I got: -9x/(3x^2+1)^3
The answer: -9x/(3x^2 +1)^5/2

y= (1 + (1 + x^2)^5)^4

dy/dx = 4(1 + (1 + x^2)^5)^3 * the derivitive of (1 + (1+ x^2)^5)

= 4(1 + (1 + x^2)^5)^3 * 5(1 + (1+ x^2))^4 * the derivitive of 1+(1+x^2)

= 4(1 + (1 + x^2)^5)^3 * 5(1 + (1+ x^2))^4 *2x

=20x (1+(1+x^2)^5)^3 (1+(1+x^2)) ^4

which is the answer given

You're out by a factor of 2 - can you see the line I bolded? You should be getting $4 \times 5 \times 2x = 40x \neq 20x$

You are right. Mistyped what I had on my paper scribbles. ha