Question 618969
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Hi,
what is Value of x
x^3-x=990
x^3-x -990 = 0         Note:  {{{x = 10}}} is one solution   1000-10 -990 = 0  
Using synthetic division  
   10	1	0	-1	-990
		10	100	990
	1	10	99	0
(x-10)(x^2 + 10x + 99)
(x^2 + 10x + 99)
{{{x = (-10 +- sqrt( 100-396))/(2) }}}
{{{x = (-10 +- sqrt( 296))/(2) }}}
{{{x = (-10 +- 2sqrt( 74))/(2) }}}
{{{x = -5 +- 8.6023 }}}
 ONe real solution, x = 10 and two imaginary solutions