solve by substitution or elimination: xy=8 and x+y= 6

Question

solve by substitution or elimination: xy=8 and     x+y= 6

anonymous · Answer

xy = 8
y = 8/x

plug 8/x into y in the equation x+y=6.

solve for x.

anonymous · Answer

would it be (-y+6)y=8

anonymous · Answer

that's a good start... no solve for y...

anonymous · Answer

*now

anonymous · Answer

actually it would be 

y = 8/x

x+y = 6

x + (8/x) = 6

solve for x.

anonymous · Answer

then i keep getting -y^2+6y-8+0 but it isnt factoring right

anonymous · Answer

i mean =0

anonymous · Answer

what would be the solution to this problem?

anonymous · Answer

im still not getting the right answer.

anonymous · Answer

you mean:  -y^2+6y-8=0 
if it doesn't factor, that means you have irrational solutions...  BUT this one does factor..

anonymous · Answer

you can actually write it out as $\large y^2-6y+8=0 $ so $\large (y-4)(y-2)=0 $

anonymous · Answer

xy=8 and x+y= 6

y = 8/x

x + (8/x) = 6

x^2 + 8 = 6x

x^2 -6x + 8 = 0

(x-4)(x-2) = 0

x = 4,2

plug into the original equation to get the y values


solve using the quadratic formula