Answers

2014-09-10T22:42:59+05:30
Given,
           x = 2-y
 => x + y = 2
cubing on both sides
 = > x³+y³+3xy(x+y) = 8
   x³ + y³ + 3xy ( 2 ) = 8
 since x+y =2
=> x³ + y³ + 6xy = 8
x³ + y³ + 6xy - 8 = 0
2 3 2
2014-09-11T12:37:50+05:30
Given x=2-y
x+y-2=0

Now x³+6xy+y³-8
    =x³+y³+(-2)³-3xy(-2)
    =[x+y+(-2)] [x²+y²+(-2)²-xy-x(-2)-y(-2)]
    =(x+y-2) (x²+y²+4-xy+2x+2y)
    =0 (x²+y²+4-xy+2x+2y)
    =0
1 5 1