Question 827944
1-2cos^2x+cos^4x
{{{cos^4(x)-2cos^2(x)+1=0}}}
{{{(cos^2(x)-1)(cos^2(x)-1)=0}}}
{{{(cos(x)+1)(cos(x)-1)(cos(x)+1)(cos(x)-1)=0}}}
..
cos(x)+1=0
cos(x)=-1(mult.2)
x=π/2,3π/2
or
cos(x)-1=0
cos(x)=1(mult.2)
x=0,π
..
see graph below:
{{{ graph( 300, 300, -4, 4, -2, 2,(cos(x))^4-2(cos(x))^2+1) }}}