Question 515573
Find the x-intercepts of f(x) = 3x^2 -7x - 5. 
1/3 x 3x^2 - 7/3x - 5/3 = 0
x^2 - 7/3x - 5/3 = 0
x^2 - 7/3x - 5/3 this is where I get lost. 
Add 5/3 to both sides
x^2 - 7/3x = 5/3
To complete the square, you have to add c, which is (b/2a)^2
{{{c = ((-7/3)/2)^2}}}
c = 49/36
Add that to both sides
{{{x^2 - 7/3x + 49/36 = 5/3 + 49/36 = 109/36}}}
Now, {{{(x - 7/6)^2 = 109/36}}}
{{{x - 7/6 = sqrt(109)/6}}}
{{{x = 7/6 + sqrt(109)/6}}}
{{{x = 7/6 - sqrt(109)/6}}}
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*[invoke solve_quadratic_equation 3,-7,-5]
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The other tutor used -3 for the x^2 term.