Question 308520
I am trying to solve the following:  x2 -4x -3 = 0.  I can get as far as 4 plus or minus the sqrt of 28 over 2.  I don't understand why this becomes 2 plus or minus the sqrt of 7.  It seems to me that it should be 2 plus or minus the sqrt of 14.

x^2-4x-3

a=1 b=-4 c=-3

root x1 = -(-4)+sqrt((-4)^2-4*1*-3  /2

x1= 4 + sqrt (16+12) /2
x1 = 4 + sqrt28 /2 
x1= (4 + sqrt( 2*2*7 ))/2
x1= (4+ sqrt4*sqrt7)/2
x1=  (4+2sqrt7)/ 2

Similarly for x2