SOLUTION: My text book is the Blitzer College Algebra book and the text asks to "Solve each equation by making an appropriate substitution" and the problem I need help with is... 9x^4=25x

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: My text book is the Blitzer College Algebra book and the text asks to "Solve each equation by making an appropriate substitution" and the problem I need help with is... 9x^4=25x      Log On


   

Question 656246: My text book is the Blitzer College Algebra book and the text asks to "Solve each equation by making an appropriate substitution" and the problem I need help with is...
9x^4=25x^2-16
Answer by Tatiana_Stebko(1539) About Me  (Show Source):
You can put this solution on YOUR website!
u=x%5E2
9u%5E2=25u-16
9u%5E2-25u%2B16=0
%289u-16%29%28u-1%29=0
9u-16=0 or u-1=0
u=16%2F9 or u=1
x%5E2=16%2F9 or x%5E2=1
x=4%2F3, x=-4%2F3, x=1, x=-1