Câu trả lời:
1, (x + y)2
2, x2 + y2
3, xy
4, a2 + 3b2
1, (x + y)2
2, x2 + y2
3, xy
4, a2 + 3b2
2x(x-y)
7,55\(\approx\)8
0,258 = (0,52)8 = 0,516
0,1254 = (0,53)4 = 0,512