г) 98²-2*98*8+8²= (98-8)²= 90²= 8100

д) 76,4²+2*76,4*13,6+13,6²= (76,4+13,6)²=90²=8100

е) ...= (85-17)(85+17)/ (85+17)²= (85-17)/(85+17)= 41/102