Question

how to find two numbers which differ by 4 and whose squares differ by 72

Answer 1

1. b - a = 4 (two numbers differ by 4)
2. b^2 - a^2 = 72 (their squares differ by 72)

solve the first one for b:

3. b = a + 4

substitute "a + 4" for "b" in the second one:

(a + 4)^2 - a^2 = 72
a^2 + 8a + 16 - a^2 = 72
8a + 16 = 72
8a = 56
a = 7

substitute "7" for "a" in equation 3:

b = 7 + 4
b = 11

Answer 2

yay! thank you!! :)