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X^2+(1-x)×(1-3x)=x, x^2+1-3x-x+3x^2=x, 4x^2-4x+1=x, 4x^2-5x+1=0, D=(-5)^2-4×4×1=25-16=9, x1=(5-корень с 9)/(4×2)=(5-3)/8=2/8=1/4, х2=(5+корень с 9)/(4×2)=(5+3)/8=8/8=1.
<span> f (x) = sin2x - x√2
</span>F' (x)=2cos2x-√2
2cos2x-√2=0
cos2x=√2/2
x=+-π/8+πn
x=π/8+πn ;-π/8+πn;17π/8+πn;15π/8+πn