x^2= 21- (sqrt x^2-9)?

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2007-02-22 16:48:05 · 3 answers · asked by lirael1019 1 in Science & Mathematics ➔ Mathematics

21-x^2=sqrt(x^2-9)
441-42x^2+x^4=x^2-9
x^4-43x^2+450=0
x^4-25x^2-18x^2+450=0
x^2(x^2-25)-18(x^2-25)=0
x^2=18 or x^2=25
x=+/-√(18) or x=+/-√(25)

2007-02-22 17:02:47 · answer #1 · answered by Maths Rocks 4 · 0⤊ 0⤋

x = -3(sqrt 2) or x = 3(sqrt 2)

2007-02-23 00:54:32 · answer #2 · answered by Derrick_k 2 · 0⤊ 1⤋

x^4=441-x^2-9
x^4+x^2-432=0

2007-02-23 00:52:13 · answer #3 · answered by Veer 3 · 0⤊ 0⤋