SOLUTION: solve X^4-10x^2+9=0 and y-2-8(sqrt)(y-2)+15=0 Thanks!

Question 66525: solve
X^4-10x^2+9=0
and
y-2-8(sqrt)(y-2)+15=0
Thanks!
Answer by Nate(3500) (Show Source): You can put this solution on YOUR website!
x^4 - 10x^2 + 9 = 0
To make it much easier, denote x^2 = y ....
(x^2)^2 - 10(x^2) + 9 = 0
(y)^2 - 10(y) + 9 = 0
y^2 - 10y + 9 = 0
(y - 9)(y - 1) = 0
(x^2 - 9)(x^2 - 1) = 0
(x + 3)(x - 3)(x + 1)(x - 1) = 0
x = -3
x = 3
x = -1
x = 1

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
y - 2 - 8*sqrt(y - 2) + 15 = 0
sqrt(y - 2) = (y + 13)/8
y - 2 = (y^2 + 26y + 169)/64
64y - 128 = y^2 + 26y + 169
0 = y^2 - 38y + 297
0 = (y^2 - 11y) + (-27y + 297)
0 = y(y - 11) - 27(y - 11)
0 = (y - 27)(y - 11)
y = 27 and y = 11

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