Chapter 5: Problem 69
\(\frac{d h_{4}}{d t}=0.5 t+2\) Integrating \(=\frac{t^{2}}{4}+2 t+5\) \(\frac{d h_{b}}{d t}=t+1\) Integrating, \(h_{b}=\frac{t^{2}}{2}+t+5\)
Chapter 5: Problem 69
\(\frac{d h_{4}}{d t}=0.5 t+2\) Integrating \(=\frac{t^{2}}{4}+2 t+5\) \(\frac{d h_{b}}{d t}=t+1\) Integrating, \(h_{b}=\frac{t^{2}}{2}+t+5\)
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Get started for free\(\mathrm{y}=\mathrm{x}^{2}+\mathrm{bx}-\mathrm{b}, \quad(1,1)\) 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 \(\Delta=\frac{1}{2} \frac{(b+1)^{2}}{(b+2)}\) \(\Rightarrow(b+1)^{2}=-4 b-8\) \(\Rightarrow b^{2}+6 b+9=0\) \((b+3)^{2}=0\) \(\Rightarrow b=-3\)
Ellipse \(\rightarrow \frac{x^{2}}{16}+\frac{y^{2}}{9}=1\) \(\Rightarrow \frac{x}{8} \frac{d x}{d t}+\frac{2 y}{9} \frac{d y}{d t}=1\) $\Rightarrow \frac{4 \sqrt{1-y^{2} / 9}}{8} \frac{d x}{d t}+\frac{2 y}{9} \times \frac{d y}{d x} \times \frac{d x}{d t}=1$ Now put \(\frac{d y}{d x}=1 \quad \& \quad y=1\) $\Rightarrow \frac{4}{6 \sqrt{2}} \frac{d x}{d t}+\frac{2}{9} \frac{d x}{d t}=1$ \(\Rightarrow \frac{d x}{d t}\left(\frac{\sqrt{2}}{3}+\frac{2}{9}\right)=1\) \(\Rightarrow \frac{d x}{d t}=\frac{9}{3 \sqrt{2}+2}\)
\(x^{2}+2 x y+2 y^{2}=45\) \(x+y+x \frac{d y}{d x}+2 y \frac{d y}{d x}=0\) \(\frac{d y}{d x}=\frac{-(x+y)}{x+2 y}=-2\) \(\Rightarrow x+y=2 x+4 y\) \(\Rightarrow x+3 y=0\) Put eq (II) in eq (I) \(9 y^{2}-6 y^{2}+2 y^{2}=45\) \(y=\pm 3\) \(x=\pm 9\) Pt \(\rightarrow(9,-3), \quad(-9,3)\)
\(y=1-a x^{2}\) \(\frac{d y}{d x}=-2 a x_{1}\) \& \(y=x^{2}\) \(\frac{d y}{d x}=2 x_{1}\) If curves are orthogonal, \(\mathrm{m}_{1} \mathrm{~m}_{2}=-1\) \(+4 a x^{2}=1\) Now \(1-a x^{2}=x^{2} \Rightarrow \frac{1}{1+a}=x^{2}\) Using eq (1), we get \(\frac{4 a}{1+a}=1\) \(\mathrm{a}=\frac{1}{3}\)
\(\mathrm{x}=\mathrm{t}^{2}+\mathrm{t}+1\) \(\frac{\mathrm{d} \mathrm{x}}{\mathrm{dt}}=2 \mathrm{t}+1\) \(\mathrm{y}=\mathrm{t}^{2}-\mathrm{t}+1\) \(\frac{\mathrm{dy}}{\mathrm{dt}}=2 \mathrm{t}-1\) \(\frac{d y}{\mathrm{~d} \mathrm{x}}=\frac{2 \mathrm{t}-1}{2 \mathrm{t}+1}\) $\Rightarrow \mathrm{y}-\left(\mathrm{t}^{2}-\mathrm{t}+1\right)=\frac{2 \mathrm{t}-1}{2 \mathrm{t}+1}\left(\mathrm{x}-\left(\mathrm{t}^{2}+\mathrm{t}+1\right)\right)$ $\Rightarrow\left(\mathrm{t}-\mathrm{t}^{2}\right)=\left(\frac{2 \mathrm{t}-1}{2 \mathrm{t}+1}\right)\left(-\left(\mathrm{t}^{2}+\mathrm{t}\right)\right)$ $\Rightarrow 2 \mathrm{t}^{2}+\mathrm{t}-2 \mathrm{t}^{3}-\mathrm{t}^{2}=\mathrm{t}^{2}+\mathrm{t}-2 \mathrm{t}^{3}-2 \mathrm{t}^{2}$ \(\Rightarrow 2 \mathrm{t}^{2}=0\) \(\Rightarrow \mathrm{t}=0\)
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