Chapter 5: Problem 38
\(y^{3}=27 x\) \(3 y^{2} \frac{d y}{d x}=27 \frac{d x}{d t}\) \(\frac{3 y^{2}}{27}<1\) \(y^{2}<9 \Rightarrow y \in(-3,3)\)
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Chapter 5: Problem 38
\(y^{3}=27 x\) \(3 y^{2} \frac{d y}{d x}=27 \frac{d x}{d t}\) \(\frac{3 y^{2}}{27}<1\) \(y^{2}<9 \Rightarrow y \in(-3,3)\)
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\(y^{2}=x\left(2-x^{2}\right)\) \(2 y \frac{d y}{d x}=2-3 x^{2}\) \(\frac{d y}{d x}=\frac{-1}{2} \quad\) at \((1,1)\) eqn of tangent \(y-1=\frac{-1}{2}(x-1)\) \(2 y+x-3=0\) Solving with curve \(\left(\frac{3-x}{2}\right)^{2}=2 x-x^{3}\) \(4 x^{3}+x^{2}-14 x+9=0\)
\(\mathrm{y}=\mathrm{x}^{2}+\mathrm{bx}-\mathrm{b}, \quad(1,1)\) lies on curve \(\frac{d y}{d x}=2 x+b=b+2\) eqn of tangent \(\Rightarrow y-1=(b+2)(x-1)\) \(x\) int \(\Rightarrow 1-\frac{1}{b+2}\) \(y\) int \(\Rightarrow 1-(b+2)\) Area of \(\Delta=\frac{1}{2} \frac{(b+1)^{2}}{(b+2)}\) \(\Rightarrow(b+1)^{2}=-4 b-8\) \(\Rightarrow b^{2}+6 b+9=0\) \((b+3)^{2}=0\) \(\Rightarrow b=-3\)
\(f(x)=\frac{x}{1-x^{2}}\) $f^{\prime}(x)=\frac{\left(1-x^{2}\right)-x(-2 x)}{\left(1-x^{2}\right)^{2}}=\frac{1+x^{2}}{\left(1-x^{2}\right)^{2}}=1$ \(1+x^{2}=1+x^{4}-2 x^{2}\) \(\Rightarrow \quad x^{2}\left(x^{2}-3\right)=0\) \(\Rightarrow x=0, \pm \sqrt{3}\) $P t \rightarrow(0,0),\left(\sqrt{3}, \frac{\sqrt{3}}{2}\right)\left(-\sqrt{3}, \frac{\sqrt{3}}{2}\right)$
slope of normal \(\Rightarrow 3 x-y+3=0\) $$ x=0 \& y=3 $$ Pt of normal \(=(0,3)\) \(\frac{d y}{d x}=\frac{-1}{3}=f^{\prime}(0)\) $\lim _{x \rightarrow 0} \frac{x^{2}}{f\left(x^{2}\right)+4 f\left(7 x^{2}\right)-5 f\left(4 x^{2}\right)}$ $\lim _{x \rightarrow 0} \frac{2 x}{x\left[2 f^{\prime}\left(x^{2}\right)+56 f^{\prime}\left(7 x^{2}\right)-40 f^{\prime}\left(4 x^{2}\right)\right]}$ \(=\frac{2}{-6}=\frac{-1}{3}\)
\(y=e^{2 x}+x^{2}\) \(\frac{d y}{d x}=2 e^{2 x}+2 x\) at \(x=0, \quad \frac{d y}{d x}=2\) \(-\frac{d x}{d y}=-\frac{1}{2}\) eqn of normal \(\rightarrow y-1=-\frac{1}{2} x\) \(\Rightarrow 2 y+x-2=0\) Distance from \((0,0)=\frac{2}{\sqrt{5}}\)
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