$A=(cos^4x-sin^4x)+(cos^4x+sin^2x.cos^2x)+3sin^2x$$=(cos^2x+sin^2x)(cos^2x-sin^2x)+cos^2x(cos^2x+sin^2x)+3sin^2x$$=cos^2x-sin^2x+cos^2x+3sin^2x=2(sin^2x+cos^2x)=2$Đúng click "V" và vote up cho Jin
$A=(cos^4x-sin^4x)+(cos^4x+sin^2x.cos^2x)+3sin^2x$$=(cos^2x+sin^2x)(cos^2x-sin^2x)+cos^2x(cos^2x+sin^2x)+3sin^2x$$=cos^2x-sin^2x+cos^2x+3sin^2x=2(sin^2x+cos^2x)=2$
$A=(cos^4x-sin^4x)+(cos^4x+sin^2x.cos^2x)+3sin^2x$$=(cos^2x+sin^2x)(cos^2x-sin^2x)+cos^2x(cos^2x+sin^2x)+3sin^2x$$=cos^2x-sin^2x+cos^2x+3sin^2x=2(sin^2x+cos^2x)=2$
Đúng click "V" và vote up cho Jin