Question

How To work this out ?

Answer 1

(a) Using the completing the square method, we need to write  into the form of  where , so
Expand to find the value of c
Notice that we get back the first two terms, the  and the .We need to get rid of the last term of '9' as the term was not in the original form. The final form will look like
Hence, 
(b)          
(c) , square root both sides      plus and minus of 2     Hence