Question

What is the slope of the line passing through the following points$\left( { - 1,7} \right),\left( { - 3,18} \right)$?

Answer 1

Hint: The slope of a line is a number that measures its steepness, usually denoted by the letter $m$.
Also we know that:
$m = \dfrac{{{y_2} - {y_1}}}{{{x_2} - {x_1}}}$
So by using the above equation we can find the slope of the line passing through the given points.

Complete step by step solution:
Given
$\left( { - 1,7} \right),\left( { - 3,18} \right)............................................\left( i \right)$
Now we have to find the slope of the line passing through the given points.
So for finding the slope of a line we have the equation:
$m = \dfrac{{{y_2} - {y_1}}}{{{x_2} - {x_1}}}..................................\left( {ii} \right)$
Such that we have to find the corresponding values and substitute it in the equation (ii) to find the slope.
So on comparing with (i) we can write:
$
  {x_1} = - 1 \\
  {x_2} = - 3 \\
  {y_1} = 7 \\
  {y_2} = 18 \\
 $
Substituting the above values in (ii) we can write:
$
  m = \dfrac{{{y_2} - {y_1}}}{{{x_2} - {x_1}}} \\
   = \dfrac{{18 - 7}}{{ - 3 - \left( { - 1} \right)}} \\
   = \dfrac{{11}}{{ - 2}} \\
   = - 5.5..........................\left( {iii} \right) \\
 $
Therefore from (iii) we can write that the slope of the line passing through the given points $\left( { - 1,7} \right),\left( { - 3,18} \right)$ would be $ - 5.5$.

Note: The slope of a line can be positive, negative, zero or undefined.
Positive slope: Here, y increases as x increases, so the line slopes upwards to the right. The slope will be a positive number.
Negative slope: Here, y decreases as x increases, so the line slopes downwards to the right. The slope will be a negative number.
Zero slope: Here, y does not change as x increases, so the line is exactly horizontal. The slope of any horizontal line is always zero.
Undefined slope: When the line is exactly vertical, it does not have a defined slope. The two x coordinates are the same, so the difference is zero.