Chapter 5: Problem 76
\(y=x^{3}-x^{2}-x+2\) \(\frac{d y}{d x}=3 x^{2}-2 x-1=0\) at \(x=1\) eqn of tangent \(y=1\) solving with curve, \(x^{3}-x^{2}-x+1=0\) \((x-1)\left(x^{2}-1\right)=0\) \(\mathrm{x}=\pm \mathrm{l}\)
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Chapter 5: Problem 76
\(y=x^{3}-x^{2}-x+2\) \(\frac{d y}{d x}=3 x^{2}-2 x-1=0\) at \(x=1\) eqn of tangent \(y=1\) solving with curve, \(x^{3}-x^{2}-x+1=0\) \((x-1)\left(x^{2}-1\right)=0\) \(\mathrm{x}=\pm \mathrm{l}\)
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\(x=t^{2}+t+1\) \(\frac{d x}{d t}=2 t+1\) \(y=t^{2}-t+1\) \(\frac{d y}{d t}=2 t-1\) \(\frac{d y}{d x}=\frac{2 t-1}{2 t+1}\) $\Rightarrow y-\left(t^{2}-t+1\right)=\frac{2 t-1}{2 t+1}\left(x-\left(t^{2}+t+1\right)\right)$ $\Rightarrow\left(t-t^{2}\right)=\left(\frac{2 t-1}{2 t+1}\right)\left(-\left(t^{2}+t\right)\right)$ \(\Rightarrow 2 t^{2}+t-2 t^{3}-t^{2}=t^{2}+t-2 t^{3}-2 t^{2}\) \(\Rightarrow 2 t^{2}=0\) \(\Rightarrow t=0\)
A) As \(\frac{a}{\sin A}=\frac{b}{\sin B}=\frac{c}{\sin C}=2 R\) \(\Rightarrow a=2 R \sin A\) \(\Rightarrow \frac{d a}{d A}=2 R \cos A\) \(\Rightarrow \frac{d a}{\cos A}=2 R d A\) Similarly, \(\frac{d b}{\cos B}=2 R d B, \frac{d c}{\cos c}=2 R d C\) \(\quad \frac{d a}{\cos A}+\frac{d b}{\cos B}+\frac{d c}{\cos C}+1=\) \(2 R(d A+d B+d C)+1\) \(\quad A s A+B+C=\pi\) \(\Rightarrow d A+d B+d C=0\) using eq (I) \(|\mathbf{m}|=1\) B) $\begin{aligned} & \Rightarrow \mathrm{m}=\pm 1 \\ \mathrm{x}^{2} \mathrm{y}^{2}=& 16 \end{aligned}$ \(2 x^{2} y \frac{d y}{d x}+2 x y^{2}=0\) \(\frac{d y}{d x}=-\frac{y}{x}=1\) Subtangent \(=y / d y / d x=2=|\mathrm{k}|\) \(\Rightarrow \mathrm{k}=\pm 2\) C) \(y=2 e^{2 x}\) \(\frac{d y}{d x}=4 e^{2 x}=4\) for yaxis $\tan ^{-1} 4=\frac{\pi}{2}-\cot ^{-1}\left(\frac{8 n-4}{3}\right)=\tan ^{-1}\left(\frac{8 n+4}{3}\right)$ \(12=|8 n-4|\) \(\mathrm{n}=2\) or \(-1\) D) \(\mathrm{x}=\underline{\mathrm{e}^{\sin y}}\) \(1=e^{\sin y} \cos y \frac{d y}{d x}\) At \((1,0) \Rightarrow \frac{d y}{d x}=1\) eqn of Normal \(\rightarrow y=-(x-1)\) \(y+x-1=0\) Area of \(\Delta=\frac{1}{2} \times 1 \times 1=\frac{1}{2}\) \(\Rightarrow|2 t+1|=3\) \(2 t+1=\pm 3 \Rightarrow t=1\) or \(-2\) $\mathrm{A} \rightarrow(\mathrm{PQ}), \mathrm{B} \rightarrow(\mathrm{RS}), \mathrm{C} \rightarrow(\mathrm{RQ}), \mathrm{D} \rightarrow(\mathrm{PS})$
$\mathrm{S}=30\left(1-\mathrm{e}^{(\ln 5 / 6) 5}\right)=30\left(1-\left(\frac{5}{6}\right)^{5}\right)$
\(y=\left(\frac{x}{2}-a\right)^{2}+a-2\) \(4(y-(a-2))=(x-2 a)^{2}\) Vertex \(\Rightarrow \mathrm{h}=2 \mathrm{a}, \mathrm{k}=\mathrm{a}-2\) Locus of vertex \(\Rightarrow \mathrm{y}=\frac{\mathrm{x}}{2}-2\) \(\Rightarrow 2 y=x-4\)
For \(y=x(c-x)\) \(\frac{d y}{d x}=c-2 x\) For \(y=x^{2}+a x+b\) \(\frac{d y}{d x}=2 x+a\) At \((1,0)\) \(0=(C-1) \Rightarrow C=1\) \(0=1+a+b, 1-2=2+a\) \(\Rightarrow \quad a=-3\) \(\Rightarrow b=2\)
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