Question

How do you solve the equation `x^2+8x-1=0` by completing the square?

Answer 1

Solution : `` x~~ 0.12(2dp) or x ~~ -8.12 (2dp)#

Explanation:

`x^2+8x-1 = 0 or (x^2+8x +4^2) -16-1 = 0` or

`(x+4)^2-17=0 or (x+4)^2 =17 or (x+4) = +- sqrt 17` or

`:. x= -4 + sqrt17 or x= -4 - sqrt17` or

`x~~ 0.12(2dp) or x ~~ -8.12 (2dp)`

Solution : `x~~ 0.12(2dp) or x ~~ -8.12 (2dp)` [Ans]