Question

(1,3), (5, k); slope = 2 K= -5 But how do you get to that answer

Answer 1

You get the answer by inserting values in slope formula and then solving for k. I'll call k, y_2

$s=\dfrac{y_2- y_1}{x_2-x_1}\Rightarrow2=\dfrac{y_2-3}{5-1} \\2=\dfrac{y_2-3}{4} \\8=y_2-3\Rightarrow y_2=11$

So the answer k = -5 is incorrect because k = 11.

Hope this helps.