Răspuns:
Explicație pas cu pas:
1
7[7^4-7(7³-7²)]-7^4=7[7^4-7³(7-1)]-7^4=
=7×7³(7-6)-7^4=7^4-7^4=0
2
(5^10:5^7-1-25):11+1=(5³-26):11+1=99:11+1=9+1=10
3
(81-80)^2019-(64-8×8)^2020+2-1=1^2019+0+2-1=2
