How do you solve 2x^2-1=7x using the quadratic formula?

1 Answer
P dilip_k
Mar 11, 2016

x=(7-sqrt57)/4 andxx=(7+sqrt57)/4

Explanation:

2x^2-1=7x
=>2x^2-7x-1=0
Dividing bothsides by 2
=>x^2-7/2x-1/2=0
=>x^2-2*x*7/4+ (7/4)^2-(7/4)^2-1/2=0
=> (x-7/4)^2-49/16-1/2=0
=> (x-7/4)^2-(49+8)/16=0
=> (x-7/4)^2-(57)/16=0
=> (x-7/4+(sqrt57)/4)(x-7/4-(sqrt57)/4)=0
:. (x=7/4-sqrt57/4)=>x=(7-sqrt57)/4

AND
(x=7/4+sqrt57/4)=>x=(7+sqrt57)/4

Related questions
See all questions in Quadratic Formula
Impact of this question
1953 views around the world
You can reuse this answer
Creative Commons License