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Mathematics 8 Online
OpenStudy (unklerhaukus):

x=-1/x

jimthompson5910 (jim_thompson5910):

x=-1/x x*x = -1 x^2 = -1 x = +-sqrt(-1) x = sqrt(-1) or x = -sqrt(-1) x = i or x = -i Note: i = sqrt(-1)

OpenStudy (unklerhaukus):

but if i is positive i=-1/i i=-1/i a positive number equals a negative number ~ or if i is negative . a negative number equals a positive number -1=-1/-i -1=1/i

OpenStudy (unklerhaukus):

is sqrt(-1) positive or negative /?

jimthompson5910 (jim_thompson5910):

if x = i, then x = -1/x i = -1/i i = (-1/i)*(i/i) i = -i/(i^2) i = -i/(-1) i = i So this confirms that x = i is a solution Do the same for x = -i to confirm it is indeed a solution

OpenStudy (unklerhaukus):

if x = -i, then x = -1 / x -i = -1 / -i -i = (-1 / -i)*(-i/-i) -i = i / i^2 -i = 1/i

OpenStudy (unklerhaukus):

-i = i/-1 = -i

OpenStudy (unklerhaukus):

so i is neither positive negative or zero, how can this be the real solution?

jimthompson5910 (jim_thompson5910):

close, but your last line should be -i = i / (-1) which then becomes -i = -i which confirms x = -i as a solution as well

jimthompson5910 (jim_thompson5910):

oh you fixed it, nvm

jimthompson5910 (jim_thompson5910):

i is the square root of negative 1, it is not a real number

OpenStudy (unklerhaukus):

is it kinda 'half negative'?

jimthompson5910 (jim_thompson5910):

what? the value of i?

OpenStudy (unklerhaukus):

yeah the value of i seams to be between negative and neutral

jimthompson5910 (jim_thompson5910):

well i don't think it's valid to think of i as positive or negative since that applies to real numbers only

OpenStudy (unklerhaukus):

ok

OpenStudy (anonymous):

\[x=-\frac{1}{x}\] \[x^2=-1\] \[x=\pm i\]

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