Question

Which equation has the solutions x = 5+/- 2 the squire root of 7 over 3

Answer 1

If you look at the quadratic formula:

x=(-b±√(b^2-4ac))/(2a)

We can say that -b=5, b=-5

If I read it right you had ±2√7 which is equal to ±√28, and we know b=-5 so:

±√(25-4ac)=±√28

And since 3=2a, a=1.5 making the above:

±√(25-6c)=±√28

25-6c=28

-6c=3

c=-0.5

So a=1.5, b=-5, and c=-0.5 thus 

y=1.5x^2-5x-0.5

We can check this by reapplying the quadratic formula to the equation above

x=(5±√(25-4(1.5)(-0.5))/3

x=(5±√(25+3))/3

x=(5±√28)/3

x=(5±√(4*7))/3

x=(5±2√7)/3