How do you solve x^2 + 3 = 9x using the quadratic formula?

1 Answer
Nghi N.
May 11, 2016

x = (9 +- sqrt69)/2

Explanation:

y = x^2 - 9x + 3 = 0.
Use the improved quadratic formula (Google, Yahoo Search).
D = d^2 = b^2 - 4ac = 81 - 12 = 69 --> d = +- sqrt69.
There are 2 real roots:
x = -b/(2a) +- d/(2a) = 9/2 +- sqrt69/2 = (9 +- sqrt69)/2

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