If P (2, m) is the midpoint of the line joining Q(m, n) and R(n, -4), find the values of m and n.

A. m = 0, n = 4

B. m = 4, n = 0

C. m = 2, n = 2

D. m = -2, n = 4

Correct Option: Answer is A

Solution:

Q(m, n) and R(n, -4)

Midpoint : P(2, m)

((m+n)/2,(n-4)/2)=(2,m)

m+n=2×2⟹m+n=4…(i)

n−4=2×m⟹n−4=2m…(ii)

Solving (i) and (ii) simultaneously,

m = 0 and n = 4.