Question

If a+b=5 and a-b=2 then find the value of a qube - b qube

Attached-question 19

Answer 1

Correct question : If ab=5 and a-b = 2, then find the value of a³ - b³.

Answer :

ab = 5 and a - b = 2

We know that,

(a - b)³ = a³ - b³ - 3ab(a - b)

》(2)³ = a³ - b³ - 3(5)(2)

》8 = a³ - b³ - 30

》a³ - b³ = 30 + 8

》a³ - b³ = 38

Thus, a³ - b³ = 38.