Question

How do you solve using the quadratic formula `x^2-25=0`?

Answer 1

If you really must use the quadratic formula,
we need to express our equation in the form:
`ax^2+bx+c=0`

`x^2-25=0`
becomes
`(1)x^2 +(0)x +(-25) =0`

The quadratic formula tells us the solution(s) is/are
`x=(-b+-sqrt(b^2-4ac))/(2a)`
or, for our example
`x=(0 +-sqrt(0^2-4(1)(-25)))/(2(1))`

`x= +-sqrt(100)/2`

`x=+-10/2`

`x=+-5`