Practicing Success
Let C be a curve given by $y=1+\sqrt{4 x-3}$, $x>\frac{3}{4}$.If P is a point on C such that the tangent at P has slope $\frac{2}{3}$, then a point through which the normal at P passes, is |
(3, -4) (1, 7) (4, -3) (2, 3) |
(1, 7) |
Let $P(\alpha, 1+\sqrt{4 \alpha-3})$ be a point on C, where $\alpha>\frac{3}{4}$ such that tangent at P has slope $\frac{2}{3}$. Now, $y=1+\sqrt{4 x-3}$ $\Rightarrow \frac{d y}{d x}=\frac{2}{\sqrt{4 x-3}} \Rightarrow\left(\frac{d y}{d x}\right)_P=\frac{2}{\sqrt{4 \alpha-3}}$ It is given that $\left(\frac{d y}{d x}\right)_P=\frac{2}{3}$ $\Rightarrow \frac{2}{\sqrt{4 \alpha-3}}=\frac{2}{3} \Rightarrow 4 \alpha-3=9 \Rightarrow \alpha=3$ So, the coordinates of P are (3, 4) The equation of the normal at P(3, 4) is $y-4=-\frac{3}{2}(x-3)$ or, $3 x+2 y-17=0$ Clearly, it basses through (1, 7). |