Dear everyone.
I'm trying to substitute expressions which are represented by square root into eq.
But, it doesn't work well as shown in the below figure.

First, the 'a' is only substituted into numerator. I'd like to know how 'a' can be also substituted into denominator.
Second, the 'b' can be substituted as I ordered to Maple.

Advice would be appreciated . Thank you !  (If you need my maple code, this will be referred in the below.)

Hi, all of you.
I'm an engineering college student. And this is my first time to check the roots using the Maple.
But I tired to solve simultaneous equations and got  into some difficulties.

Acutually I'd like to get 6 roots[ A[i], t[i], i=(1,2,3).
Initial values are A[1]+A[2]+A[3]=1 and t[1]=0.

So I've simplified for 4 equations to get 4 root and to ask you.
Below, there is my code to get A[2], A[3], t[2] and t[3]. But it doesn't work well.