L(4,-1) is the midpoint of the line joining points P(5,a) and Q(b,1).Find the values of a and b.

Answer 1

L(4,-1) is the midpoint between P(5,a) and Q(b,1)

b=3

a=-5

(5+b)/2 = 4

5+b= 8

b =8-5= 3

the midpoint coordinates are the average of the end point coordinates

(a+3)/2=-1

a+3 =-2

a = -5

It may help to plot the points with at least a rough sketch