what should be subtracted from 4(sin^4 30^o+cos^4 60a^o)-2(cos^2 45^o-sin2 60^o) to get 0
what a strange question.
4(sin^4 30^o+cos^4 60a^o)-2(cos^2 45^o-sin2 60^o) - [4(sin^4 30^o+cos^4 60a^o)-2(cos^2 45^o-sin2 60^o)] =0
perhaps you want to know what the value is ...
\(4(sin^4 30^o+cos^4 60a^o)-2(cos^2 45^o-sin2 60^o)\\ =4(\frac{1}{2^4}+cos^4 60a^o)-2(\frac{1}{2}-sin2 60^o)\\ \text {interpretation of meaning (possible errors)}\\ =4(\frac{1}{2^4}+cos^4 60^o)-2(\frac{1}{2}-sin^2 60^o)\\ =4(\frac{1}{2^4}+\frac{1}{2^4})-2(\frac{1}{2}-\frac{3}{4})\\ =4(\frac{2}{2^4})-2(\frac{-1}{4})\\ =\frac{1}{2}+\frac{1}{2}\\ =1 \)
so
4(sin^4 30^o+cos^4 60^o)-2(cos^2 45^o-sin^2 60^o) -1 =0