If x - y = 4 and x3 - y3 = 316, y > 0 then the value of x4 - y4 is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 2320
x - y = 4..............(1)
on cubing both sides we get,
x3 - y3 - 3xy(x - y) = 64
-12xy = 64 - 316
xy = 21(7 × 3).........(2)
By eq one and 2 we get,
x = 7 and y = 3.
x4 - y4 = 74 - 34 = 2401 - 81
= 2320.