SOLUTION: xy=3 5x-6y=6 by substitution method

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Question 566012: xy=3
5x-6y=6
by substitution method
Answer by mananth(16946) About Me  (Show Source):
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xy=3
y= 3/x
substitute y in the equation
5x-6y=6
5x -6*(3/x)=6
multiply the equation by x
5x^2-18=6x
5x^2-6x-18=0
Find the roots of the equation by quadratic formula

a= 5 , b= -6 , c= -18

b^2-4ac= 36 + 360
b^2-4ac= 396
%09sqrt%28%09396%09%29=%0919.9%09
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=( 6 + 19.9 )/ 10
x1= 2.59
x2=( 6 -19.9 ) / 10
x2= -1.39

if x = 2.59 y = 3/2.59 = 1.16
(2.59,1.16)
If x= -1.39 y= 3/-1.39=-2.16
(-1.39,-2.16)