SOLUTION: For the function f(x)=x + 12/x , find x when f(x)=8 So I know f(x)=8 is like y=8, and I'm trying to find x. f(8)= x + 12/x Now I'm lost. Should I be multiplying both sides of

Question 349024: For the function f(x)=x + 12/x , find x when f(x)=8
So I know f(x)=8 is like y=8, and I'm trying to find x.
f(8)= x + 12/x
Now I'm lost. Should I be multiplying both sides of the equation by the reciprocal of 12/x?
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Is the equation or is it ??? Please clarify.

Edit: Thanks for the clarification.

Start with the given equation.

Plug in . In other words, replace f(x) with 8.

Multiply EVERY term by x to clear out the fraction.

Subtract 8x from both sides.

Notice that the quadratic is in the form of where , , and

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

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.

So the solutions are or

If you need more help, email me at jim_thompson5910@hotmail.com

Also, feel free to check out my tutoring website

Jim
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