The sum of the roots of the quadratic equation 3x2-9x+5=0 is.....
Answers
Answer:
3x^2 - 9x - 5 = 0. Can't be factored. Try completing the square. Divide all terms by 3.
x^2 - 3x - 5/3 = 0. Divide - 3 by 2, square it, and add it to both sides of the equation.
x^2 - 3x + (- 3/2)^2 - 5/3 = (- 3/2)^2. Square - 3/2 on both sides of the equation.
x^2 - 3x + 9/4 - 5/3 = 9/4. Add 5/3 to both sides.
x^2 - 3x + 9/4 = 9/4 + 5/3. Find a common denominator on the right side which is 12 and change the fractions to twelveths.
x^2 - 3x + 9/4 = 27/12 + 20/12. Combine the fractions on the right side.
x^2 - 3x + 9/4 = 47/12. Factor the left side.
(x - 3/2)(x - 3/2) = 47/12.
(x - 3/2)^2 = 47/12. Take the square root of both sides.
x - 3/2 = +/- sq rt(47/12). Add 3/2 to both sides.
x = 3/2 +/- sq rt(47/12). Two answers.
x = 3/2 + sq rt(47/12). One Answer.
x = 3/2 - sq rt(47/12). The other Answer.
You could also use the Quadratic Equation to solve it. a = 3, b = - 9 and c = - 5.