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Step * of Lemma derivative-minus-minus

∀I:Interval. ∀f,g:I ⟶ℝ.  (d(f[x])/dx = λx.-(g[x]) on I ⇒ d(-(f[x]))/dx = λx.g[x] on I)
BY
{ (Auto
   THEN (Assert d(-(f[x]))/dx = λx.-(-(g[x])) on I BY
               (BLemma `derivative-minus` THEN Auto))
   THEN DerivativeFunctionality (-1)
   THEN Auto) }

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Latex:

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Latex:
\mforall{}I:Interval.  \mforall{}f,g:I  {}\mrightarrow{}\mBbbR{}.    (d(f[x])/dx  =  \mlambda{}x.-(g[x])  on  I  {}\mRightarrow{}  d(-(f[x]))/dx  =  \mlambda{}x.g[x]  on  I)


By

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Latex:
(Auto
  THEN  (Assert  d(-(f[x]))/dx  =  \mlambda{}x.-(-(g[x]))  on  I  BY
                          (BLemma  `derivative-minus`  THEN  Auto))
  THEN  DerivativeFunctionality  (-1)
  THEN  Auto)

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