Question

The difference in volumes of two cubes is 152 m3 and the difference in their one face areas is 20 m2. If the sum of their edge is 10 m, the product of their edge is ?

Answer 1

Answer:

Correct answer---

Let the edges of the two cubes be x and y metres

Then, x3 - y3 = 152

and x2 - y2 = 20

Also, x + y = 10

So, x - y = (x2 - y2) / (x + y) = 20/10 = 2

Now, (x3 - y3) / (x - y) = 152/2

⇒ x2 + y2 + xy = 76

⇒ (x + y)2 - xy = 76

⇒ xy = (x + y)2 - 76 = (10)2 - 76 = 24