Solve `x^2-4x-4=0`

### 1 Answer | Add Yours

To solve this equation, we cannot factor it using integers or rational values, so instead we need to use the quadratic formula.

For the quadratic equation `ax^2+bx+c=0` , the quadratic formula is

`x={-b+-sqrt{b^2-4ac}}/{2a}`

In this case, a=1, b=-4 and c=-4, so the solutions to the equation are

`x={4+-sqrt{16-4(-4)}}/2` simplify the square root

`={4+-sqrt32}/2` simplify the radical

`={4+-sqrt16sqrt2}/2`

`={4+-4sqrt2}/2` cancel common factor of 2 in numerator and denominator

`=2+-2sqrt2`

**The solutions of the equation are `x=2+2sqrt2` and `x=2-sqrt2` .**

### Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes