Question

How do you solve using completing the square method `y=x^2-12x +40`?

Answer 1

Solution: `x= 6+2i and x= 6-2i`

Explanation:

Let `x^2-12x+40 =0 or(x^2-12x)+40=0` or

`(x^2-12x +36)-36+40=0` or

`(x-6)^2=-4 or (x-6)=+-sqrt (-4)` or

`(x-6)=+-sqrt (4i^2) [i^2=-1]` or

`x-6 =+-2i or x = 6+- 2i :. x= 6+2i and x= 6-2i`

Solution: `x= 6+2i and x= 6-2i` [Ans]