SOLUTION: what are the exact solutions x^2+18x+81=16

Question 215124: what are the exact solutions x^2+18x+81=16
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
There are two ways to do this:

Method # 1

Start with the given equation.

Get every term to the left side.

Combine like terms.

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

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

Method # 2

Start with the given equation.

Factor the left side

Take the square root of both sides.

or Break up the "plus/minus" to form two equations.

or Take the square root of to get .

or Subtract from both sides.

or Combine like terms.

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

Answer:

So the solutions are or (which is what we got earlier).

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