Question

if x minus 2 Y is equals to 11 and x y is equals to 8 find the value of x cube minus 8 y cube


answer fast!!!

Answer 1

We got x - 2y = 11    and xy = 8

x³ - 8y³ = (x - 2y ) (x² + 4y² + xy)

So we have to find out first x² + 4y²

(x - 2y)² = x² + 4y² - 2xy

11² = x² + 4y² - 16    (2 x8 in which 8 is xy)

121 + 16 = x² + 4y²

x² + 4x² = 137

Now come back to our first formula

x³ - 8y³ = (x - 2y ) (x² + 4y² + xy)

x³ - 8y³ = (11 ) 137 + 8)

x³ - 8y³ = 11 x 145 = 1595

Answer 2

Hope this is the answer and it is helpful