
Laura I. answered 10/03/15
Tutor
New to Wyzant
Patient Tutor for Math and Science
For this, you need to know that the quadratic equation is x=[-b ±√(b2-4ac) ]/ 2a.
In the quadratic equation, a b and c refer to the coefficients in front of the variable as well as the number term without the variable. In the equation x2+6x+3=0, a is the number in front of x2 which in this case is 1 (there is only 1 x2 term). The b is 6 and c is 3.
Now it's just a matter of substituting a b and c within the quadratic equation: x= [-6 ± √(62-4•1•3)] / 2•1 which is the same as x= [-6 ±√(36 -12)] /2. Continuing on, x=[-6 ± √(24)]/2 so one solution is x=(-6 +√24)/2 while the other is x= (-6 –√24)/2.
From here, you can split the -6 from √24 from both solutions by making them separate fractions that have the same denominator: x= (-6/2)+(√24/2) and x= (-6/2)-(√24/2). Now the solutions are x= -3 +√24/2 and x= -3 –√24/2 . You can simplify further by taking out the factors that make up 24 (build a factor tree!), so √24 becomes 2√6. 2√6 is being divided by 2 so the 2's cancel leaving √6.
Putting it all together, you have the solutions x= -3 + √6 and x= -3 - √6 .