Question

find the value of :x3 - 8y3 - 36xy - 216 when x=2y + 6

Answer 1

x=2y+6
x=3
y=3
x3 - 8y3 -36xy -216
9 -72-324-216
-603

HOPE IT HELPS

Answer 2

Answer:

so given

x = 2y+6

⇒ x - 2y = 6      ...... (i)

cubing both sides

⇒ x³ - 8y³ - 6xy(x - 2y) = 216

⇒ x³ - 8y³ - 6xy(6) = 216      {since , x - 2y = 6 from i}

⇒x³ - 8y³ - 36xy - 216 = 0

so the value of x³ - 8y³ - 36xy - 216 = 0  ANSWER