SOLUTION: square root of y+8 minus square root of y-6 equals -3, Help! I have tried isolating one of the radicals and raising both sides to the power of the index, then isolating the radica

Algebra ->  Radicals -> SOLUTION: square root of y+8 minus square root of y-6 equals -3, Help! I have tried isolating one of the radicals and raising both sides to the power of the index, then isolating the radica      Log On


   

Question 567489: square root of y+8 minus square root of y-6 equals -3, Help!
I have tried isolating one of the radicals and raising both sides to the power of the index, then isolating the radical again, but webassign isnt taking my answer! I come up with 6 25/36.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
square root of y+8 minus square root of y-6 equals -3,
:
sqrt%28y%2B8%29+-+sqrt%28y-6%29 = -3
:
sqrt%28y%2B8%29+=+sqrt%28y-6%29 - 3
square both sides
y + 8 = [sqrt%28y-6%29 - 3]^2
FOIL the right side
y + 8 = %28y-6%29+-+3sqrt%28y-6%29+-+3sqrt%28y-6%29+%2B+9
:
y + 8 = y + 3 - 6sqrt%28y-6%29
:
y + 8 = y + 3 - 6sqrt%28y-6%29
y - y + 8 - 3 = 6sqrt%28y-6%29
5 = 6sqrt%28y-6%29
square both side again
25 = 36(y-6)
25 = 36y - 216
25 + 216 = 36y
241 = 36y
y = 241%2F36
y = 6.7 which about what you got, but the trouble is if we substitute this in the original problem we get a +3 not -3, therefore there is no solution