Question

For what value of x, will the points (-1,x),(-3,2) and (-4,4) lie on a line?

• A. -3
• B. 3
• C. -2
• D. 2

Answer 1

The correct option is C -2

$A(-1,x),B(-3,2),C(-4,4)$ lie on a line

$\therefore \frac{1}{2}\left|x_1\right(y_2-y_3)+x_2(y_3-y_1)+x_3(y_1-y_2\left)\right|=0$

$\frac{1}{2}|-1(2-4)+-3(4-x)+-4(x-2\left)\right|=0$

$\frac{1}{2}|-1(-2)-3(4-x)-4(x-2\left)\right|=0$

$\frac{1}{2}|2-3\times 4+3x-4x+4\times 2|=0$

$\frac{1}{2}|2-12+3x-4x+8|=0$

$\frac{1}{2}|-2-x|=0$

$-2-x=0$

$x=-2$.