Rút gọn: A = (1 + 2)^2 - (1^3 + 2^3) + 3^3; B = 7^10 : 7^8 + (3^2 + 4^2 - 5^2)^3

1. Rút gọn
1, A= ( 1+2)^2 - ( 1^3 + 2^3) + 3^3
2, B= 7^10 : 7^8 + ( 3^2 + 4^2 - 5^2) ^3
3, C= /1-2-3/ + (-2)
4, D= 7. /x/ - 3x ; ( x >;= 0)
5, E= /x/ + /x+1/ + /x+2/ (x.10
2. Tìm x=?
1, /x+1/5/= 4/5
2, (x-8). 3/4 =0
3, (x-7) . (3/4+ 1/2) = 0
4, x-10/2 + x-10/3 =0
5, x-100/24 + x-98/26 + x-96/28 = 3