Please help! Thanks!

Question

If m² + n² = 140 and mn=49, what is the value of (m-n)²?

a. 0

b. 24

c. 238

d. 42

Answer 1

m^2 + n^2 = 140

mn= 49

(m-n)^2 = m^2 - 2mn + n^2 = 140 -2mn = 140 -2(49) = 140 - 98 = 42

(m-n)^2 = 42

d is correct