16а^4-4а^2у+4а^2у-у^2=16а^4-у^2
по формуле (а-b)×(a+b)=a^2 -b^2
Y=x²
a) y=(-3)²=9
б) y=(2/3)²=4/9
В)
0.(12) = 12/99
1.0(12) = 1 + 1/10 * 12/99 = 1 + 12/990 = 990/990 + 12/990 = 1002/990
8.7(21) = 87/10 + 21/990 = 8613/990 + 21/990 = 8634/990
г)
23.5(0) = 23.5 = 235/10
23.5(1) = 235/10 + 1/90 = 2115/90 + 1/90 = 2116/90
23.5(13) = 235/10 + 13/990 = 23265/990 + 13/990 = 23278/990
23.5(127) = 235/10 + 127/9990 = 234765/9990 + 127/9990 = 234892/9990