SOLUTION: I really need help with this quadratic equation and check. Thank you for all your help. 1/4x² + 17/4 = 2x

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Question 329607: I really need help with this quadratic equation and check. Thank you for all your help.
1/4x² + 17/4 = 2x

Found 2 solutions by Fombitz, Theo:
Answer by Fombitz(32388)   (Show Source): You can put this solution on YOUR website!

First multiply by 4.


Complete the square in x.
Add, to both sides, the square of (1/2) of the x coefficient.


Take the square root of both sides.

where

Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
I believe you are saying:

(1/4)*x^2 + (17/4) = 2*x

If this is not the case, then send me an email with a clarification.

You can start by subtracting 2*x from both sides of the equation to get:

(1/4)*x^2 - 2*x + (17/4) = 0

Multiply both sides of this equation by 4 to get:

x^2 - 8*x + 17 = 0

Complete the squares on the (x^2 - 8*x) part to get:

(x-4)^2 - 16 + 17 = 0

Add 16 and subtract 17 from both sides of this equation to get:

(x-4)^2 = -1

Take the square root of both sides of this equation to get x-4 = +/- square root of (-1).

Since square root of (-1) is not a real value, then this quadratic equation does not have any real roots.

It has imaginary, or complex roots, complex being a combination of real and imaginary.

A graph of your original equation is shown below:



You can see that the graph of this equation does not cross the x-axis, therefore this equation doesn't have any real roots.

The roots that we did find are:

x = 4 +/- square root of (-1)

Since square root of (-1) is equal to i, then the roots become:

x = 4 +/- i.

Once again, these are not real roots.

These are complex roots, because they are a combination of a real part (the 4) and an imaginary part (the i, where i = square root of (-1)).

If you had used the quadratic formula, you would have gotten the same answer.

The quadratic formula is x = (-b +/- square root of (b^2-4ac) / (2a).

In your equation of x^2 - 8*x + 17 = 0,

a = 1
b = -8
c = 17

The quadratic formula becomes:

x = (-(-8) +/- square root of (64-4*1*17)) / (2*1) which becomes:

x = (8 +/- square root of (64 - 68)) / 2 which becomes:

x = (8 +/- square root of (-4) / 2 which becomes:

x = (8 +/- square root of (4*-1) / 2 which becomes:

x = (8 +/- 2 * square root of (-1) / 2 which becomes:

x = 4 +/- square root of (-1).

Since square root of (-1) is equal to i, then the solution becomes

x = 4 +/- i.

This is the same answer we derived using the completing the squares method.










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