SOLUTION: For the following, solve. Find exact solutions {{{y^4-3y^2=-1}}}

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Question 142982: For the following, solve. Find exact solutions


Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Start with the given equation


Add 1 to both sides


Let . So this means that


Replace with . Replace with .


Let's use the quadratic formula to solve for x:


Starting with the general quadratic



the general solution using the quadratic equation is:





So lets solve ( notice , , and )




Plug in a=1, b=-3, and c=1



Negate -3 to get 3



Square -3 to get 9 (note: remember when you square -3, you must square the negative as well. This is because .)



Multiply to get



Combine like terms in the radicand (everything under the square root)



Simplify the square root (note: If you need help with simplifying the square root, check out this solver)



Multiply 2 and 1 to get 2

So now the expression breaks down into two parts

or



So the solutions in terms of x are



or



But remember, we let . So this means


or


Take the square root of both sides in each case

or


So after breaking up the expressions, we get the four solutions

, , ,

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