Question

高一数学。怎么由上面一个式子得到下面的式子的？写出过程。谢谢。

Answer 1

f(x)=sin2x+cos2x=√2（√2/2*sin2x+√2/2cos2x)=
√2(sin2x*cosπ/4+cos2x*sinπ/4)
=√2(sin(2x+π/4)

Answer 2

f(x)=sin2x+cos2x
=√2(1/√2•sin2x+1/√2•cos2x)
=√2(√2/2•sin2x+√2/2•cos2x)
=√2(cos45°•sin2x+sin45°•cos2x)
=√2•sin(2x+45°)
=√2sin(2x+π/4)

Answer 3

f(-x)=2^(-x)/(1+4^(-x))=2^x/(1+4^x)=-f(x) f(x)=-2^x/(1+4^x) x∈[0,1) f(x)=-2^x/(1+4^x) x∈(-1,0)