y=根号下(cosx²)求导-xtan(x²)根号下(cosx²)

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y=根号下(cosx²)求导-xtan(x²)根号下(cosx²)
y=根号下(cosx²)求导
-xtan(x²)根号下(cosx²)

y=根号下(cosx²)求导-xtan(x²)根号下(cosx²)
y = [根号下(cosx²)]'
=[(cosx²)^(1/2)]'
= (1/2)×(cosx²)^(-1/2)×(cosx²)'
= (1/2)×(cosx²)^(-1/2)×(-sinx²)×(x²)'
= (1/2)×(cosx²)^(-1/2)×(-sinx²)×(2x)
= (cosx²)^(-1/2)×(-sinx²)×(x)
= - x(cosx²)^(1/2)×sinx²/cosx²
= -x(cosx²)^(1/2)× tan(x²)

y=根号(cosx^2)
那么y'=1/2 ×(cosx^2)^(1/2 -1) ×(cosx^2)'
=1/2 ×(cosx^2(-1/2)×(-sinx^2)×(x^2)'
=-xsin(x^2)/cos(x^2)
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令u=cosv v=x² y=根号下u
则dy/dx=dy/du *du/dv *dv/dx
=(1/2)u^(-1/2) *(-sinv)*2x
=1/2(cosx²)^(-1/2)*(-sinx²)*2x
=-xsinx²*(cosx²)^(-1/2)

y'=(√cosx²)'
=(1/2)/(√cosx²)*(cosx²)'
=(1/(2√cosx²))*(-sinx²)(x²)'
=(-sinx²/(2√cosx²))*(2x)
=-2xsinx²/(2√cosx²)
=-xsinx²/√cosx².