SOLUTION: Solve the following 15x^4-28x^2+5=0

Question 480750: Solve the following 15x^4-28x^2+5=0
Answer by emargo19(101) (Show Source): You can put this solution on YOUR website!
Start with the given equation.

Let . So this means that

Replace with and with "z"

Notice we have a quadratic equation in the form of where , , and

Let's use the quadratic formula to solve for z

Start with the quadratic formula

Plug in , , and

Negate to get .

Square to get .

Multiply to get

Subtract from to get

Multiply and to get .

Take the square root of to get .

or Break up the expression.

or Combine like terms.

or Simplify.

-----------------------------------------

Since we let , we need to plug that in:

Start with the first solution for "z"

Plug in

Take the square root of both sides.

or Break up the "plus/minus".

or Simplify the square root.

So the first two solutions are or

------------------------------------------------

Start with the second solution for "z"

Plug in

Take the square root of both sides.

or Break up the "plus/minus".

or Simplify the square root.

So the next two solutions are or

============================================================

Answer:

So the four solutions are:

, , or
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