2006-07-25 18:28:35 · 4 answers · asked by y0marc 1 in Education & Reference ➔ Higher Education (University +)
x + 1/x = 8
x^2 + 1 = 8x
x^2 - 8x +1 = 0
x = 4 +/- sqrt(15)
2006-07-25 18:46:33 · answer #1 · answered by David S 5 · 1⤊ 0⤋
Let the number be 'x'. So its reciprocal will be ' 1/x ' .
According to the question - x + 1/x = 8
Taking the LCM , - x^2 + 1 = 8x
x^2 - 8x + 1 = 0
x = 3.87 or x = 0.26 ( by factorising)
2006-07-26 01:33:39 · answer #2 · answered by K.P. 3 · 0⤊ 0⤋
the eqn is:
x+1/x=8
i.e. x^2 +1 = 8x
i.e. x^2 -8x+1=0
use {–b+/-sqrt( b^2-4ac)}/2a, where the eqn is: ax+bx^2+c=0
i.e. {8+/- sqrt(64-4)}/2
i.e. (8+/- 7.745)2
i.e.15.745/2 or 0.255/2
i.e. 7.8725 or 0.1275
you can try looking at the formula in http://www.purplemath.com/modules/quadform.htm
2006-07-26 01:51:13 · answer #3 · answered by Payal G 2 · 0⤊ 0⤋
[8+/- the sqrt (60)] /2
the below link should give you a decent idea of what to do , but when i tried it myself i couldn't factor it so i used the quadratic formula
2006-07-26 01:44:45 · answer #4 · answered by onanist13 3 · 0⤊ 0⤋