How do you solve using the completing the square method #2x^2-8x-3=0#?

Question

2490 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-06-15T20:18:54

See below

First extracting common factor

#2(x^2-4x-3/2)=0#

Now complete square

#2((x-2)^2-4-3/2)=0# now re-arrange terms

#2((x-2)^2-11/2)=0#

Now, using identity #(a+b)(a-b)=a^2-b^2#

#2((x-2+sqrt(11/2))(x-2-sqrt(11/2)))=0#

Roots are #2+sqrt(11/2)# and #2-sqrt(11/2)#