1) [(-2/5)¹⁰]² : (-2/5)¹⁸= (-2/5)²⁰ : (-2/5)¹⁸= (-2/5)²= 4/25
2)(-2/3)²+ (1/4)²= 4/9 +1/16= (64+9)/144= 73/144
3) 2 intregi 1/9= 19/9
1,(2)=1 intreg 2/9= 11/9
(-3 +4/3 )²= [ (-9+4)/3]²= ( -5/3)²= 25/9
25/9 : ( 19/9 +11/9)= 25/9 : 30/9= 25/9 * 9/30= 25/30= 5/6
4)[(3/4)² + 1 -(-1)]⁻¹= ( 9/16 +1 +1) ⁻¹= [(9+16+16)/16]⁻¹=
= (41/16)⁻¹= 1/ (41/16)¹= 16/41