#dy/dx= color (blue)((dy/dt)/color (brown)(dx/dt)#
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#color (blue)(dy/dt) and color (brown)(dx/dt)# are determined by
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applying the quotient rule.
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#color (blue)(dy/dt=?#
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#dy/dt=((2t+1)'xxt-t'xx (2t+1))/t^2#
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#dy/dt=(2xxt-1xx (2t+1))/t^2#
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#dy/dt=(2t-2t-1)/t^2#
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#color (blue)(dy/dt=-1/t^2#
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#color (brown)(dx/dt=?#
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#dx/dt=((t-1)'xxt-t'xx (t-1))/t^2#
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#dx/dt=(1xxt-1xx (t-1))/t^2#
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#dx/dt=(t-t+1)/t^2#
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#color (brown)(dx/dt=1/t^2#
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#dy/dx=(color (blue)(dy/dt))/(color (brown)(dx/dt))#
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#dy/dx=(color (blue)(-1/t^2))/(color (brown)(1/t^2))#
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#dy/dx=-1/t^2xxt^2/1#
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#therefore dy/dx=-1#