ExamGOAL
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59
Subjective

The equation of the line through the intersection of the lines $2 x-3 y=0$ and $4 x-5 y=2$ and

Column I Column II
(i) through the point $(2,1)$ is (a) $2x-y=4$
(ii) perpendicular to the line $x+2y+1=0$ is (b) $x+y-5=0$
(iii) parallel to the line $3x-4y+5=0$ is (c)` $x-y-1=0$
(iv) equally inclined to the axes is (d) $3x-4y-1=0$

Explanation

$$\begin{aligned} \text{Given equation of the lines are}\quad & 2 x-3 y=0 \quad \text{... (i)}\\ \text{and}\quad & 4 x-5 y=2\quad \text{... (ii)} \end{aligned}$$

From Eq. (i), put $x=\frac{3 y}{2}$ in Eq. (ii), we get

$$\begin{aligned} 4 \cdot \frac{(3 y)}{2}-5 y & =2 \\ \Rightarrow \quad 6 y-5 y & =2 \\ \Rightarrow \quad y & =2 \end{aligned}$$

Now, put $y=2$ in Eq. (i), we get $$x=3$$

So, the intersection points are $(3,2)$.

(i) The equation of the line passes through the point $(3,2)$ and $(2,1)$, is

$$\begin{array}{rlrl} & y-2 & =\frac{1-2}{2-3}(x-3) \\ \Rightarrow & y-2 & =(x-3) \\ \Rightarrow & x-y-1 & =0 \end{array}$$

(ii) If the required line is perpendicular to the line $x+2 y+1=0$

$\because$ Slope of the required line $=2$

$\therefore$ Equation of the line is

$$y-2=2(x-3)$$

$$\Rightarrow \quad 2 x-y-4=0$$

(iii) If the required line is parallel to the line $3 x-4 y+5=0$, then the slope of the required line $=\frac{3}{4}$

$\therefore$ Equation of the required line is

$$y-2=\frac{3}{4}(x-3)$$

$$\begin{array}{l} \Rightarrow & 4 y-8=3 x-9 \\ \Rightarrow & 3 x-4 y-1=0 \end{array}$$

(iv) If the line is equally inclined to the $X$-axis, then

$$m= \pm \tan 45 \Upsilon= \pm 1$$

$\therefore$ Equation of the line is

$$\begin{array}{l} & y-2 & =-1(x-3) \text{[taking negative value]}\\ \Rightarrow & y-2 & =-x+3 \\ \Rightarrow & x+y-5 & =0 \end{array}$$

So, the correct matches are (a) $\rightarrow$ (iii), (b) $\rightarrow$ (i), (c) $\rightarrow$ (iv), (d) $\rightarrow$ (ii).