if x²+1/x²=7,find the value of x³+1/x³
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x²+1/x²=7
(x+1/x)²=x²+1/x²+2 x×1/x
(x+1/x)²=7+2=9
x+1/x= 3
♦===============
(x+1/x)³=x³+1/x³+3(x+1/x)
3³=x³+1/x³+3(3)
27=x³+1/x³+9
27-9= x³+1/x³
18= x³+1/x³
@:-)
x²+1/x²=7
(x+1/x)²=x²+1/x²+2 x×1/x
(x+1/x)²=7+2=9
x+1/x= 3
♦===============
(x+1/x)³=x³+1/x³+3(x+1/x)
3³=x³+1/x³+3(3)
27=x³+1/x³+9
27-9= x³+1/x³
18= x³+1/x³
@:-)
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