Question
Sun September 22, 2013 By: Nilangi

if x=2y+6 then find the value of xcube-8ycube-36xy-216

Expert Reply
Sun September 22, 2013

Given: x=2y+6

x-2y-6=0 ----------------- (1)

x3- 8y3- 216 - 36xy

= (x)3+ (-2y)3+ (-6)- 3*x*(-2y)*(-6)

=(x-2y-6) (x2+4y2+36+2xy-12y+6x)

= 0 (x2+4y2+36+2xy-12y+6x) (from equation (1) )

=0

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