# SOLUTION: Could you help me solve: 9x^4-21x^2+10=0

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 Question 273250: Could you help me solve: 9x^4-21x^2+10=0Answer by Theo(3504)   (Show Source): You can put this solution on YOUR website!9x^4-21x^2+10=0 Let k = x^2 Equation becomes: 9k^2 - 21k + 10 = 0 This equations factors out to be: (3k-5) * (3k-2) = 0 solve for k to get: k = 5/3 or k = 2/3 Since we set k = x^2, then: k = 5/3 is the same as x^2 = 5/3 k = 2/3 is the same as x^2 = 2/3 Solving for x, we get: x = +/- x = +/- plug these into your original equation to see if they hold up. your original equation is: 9x^4 - 21x^2 + 10 = 0 I plugged these values into that equation and they all proved to be true so the values are good. For example: When x = , the equation becomes: which becomes: 25 - 35 + 10 = 0 which becomes: -10 + 10 = 0 which becomes: 0 = 0 confirming that the value of is good. Your answers are: x = plus or minus and: x = plus or minus