Question

If x-y = 5, then find the value of x^3 - y^3 - 15xy - 100 is equal to​

Answer 1

Answer:

25

Step-by-step explanation:

{since a³-b³= (a-b)(a²+ab+b²)}

(x-y)(x²+xy+y²)-15xy-100

5(x²+xy+y²)-15xy-100

5x²+5xy+5y²-15xy-100

5x²+5y²-10xy-100

5(x²+y²-2xy-20)

{since (a-b)²=a²+b²-2ab}

5[(x-y)²-20]

5[(5)²-20]

5(25-20)

5(5)

25