(a+4b,a-b) and (a-3b,a) find the length of the line segment joining this pair of points.
use the usual distance formula:
√(((a-3b)-(a+4b))^2 + (a-(a-b))^2)
= √(-7b)^2+(b)^2)
= √(50b^2)
= 5b√2
√(((a-3b)-(a+4b))^2 + (a-(a-b))^2)
= √(-7b)^2+(b)^2)
= √(50b^2)
= 5b√2