Question

Find the value of $k$ so that the slope of the line through $(2,-k)$ and $(-1,4)$ is $1$

Answer 1

Slope = $m=\frac{y_2-y_1}{x_2-x_1}$ where $x_1=2,y_1=-k$

$x_2=-1,y_2=4$

$\Rightarrow 1=\frac{4-(-k)}{-1-2}$

$\Rightarrow -3=4+k$

$\Rightarrow k=-7$