Question

Find the value of 'b' for which the points A(-1,2) ,B(-1,b) and (-3 ,-4) are collinear

Answer 1

Value of b is 2

Step-by-step explanation:

If two slopes show 1 as a result, $m_1 = m_2$, then the three points are collinear.

Here, Let the three points be A = (-1,2), B = (-1,b) & C = (-3,-4)  

Applying, slope equations,

⇒ $\frac {y_3 - y_1}{x_3 - x_1} = \frac {y_3 - y_2}{x_3 - x_2}$

⇒ $\frac {-4 - 2}{-3 - (-1)} = \frac {-4 - b}{-3 - (-1)}$

⇒ $\frac {-6}{-2} = \frac {-4 - b}{-2}$

⇒ $-6 = -4 -b$

⇒ $6 - 4 = b$

⇒ $b = 2$

So, value of b = 2