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Quadratics

Hi,
I'm a it confused about the difference between the standard format for a quadratic equation: ax^2 + bx + c = 0
and the quadratic formula x = -b+- root(b^2-4ac) / 2a

Why are there two?
What is the point of using the standard format to solve an equation if you can just use the quadratic formula?

Why do you get different answers to solving (for example) : 3x^2 + 7x - 6 = 0
I get x = 2/3 & x = -3 using standard equation but

x = -0.317
x = - 2.017 using the formula

Could someone this to me please?
What is the point of solving using the equation if they call all be solved using the formula?
(edited 3 years ago)
Original post by DJFearRoss
Hi,
I'm a it confused about the difference between the standard format for a quadratic equation: ax^2 + bx + c = 0
and the quadratic formula x = -b+- root(b^2-4ac) / 2a

Why are there two?
What is the point of using the standard format to solve an equation if you can just use the quadratic formula?

Why do you get different answers to solving (for example) : 3x^2 + 7x - 6 = 0
I get x = 2/3 & x = -3 using standard equation but

x = -0.317
x = - 2.017 using the formula

Could someone this to me please?
What is the point of solving using the equation if they call all be solved using the formula?


If you don't have it in that format then it is not so obvious what a, b and c are.

Your formula as you have written it here is incorrect. It should be

x=−b±b2−4ac2a\displaystyle x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}
Quadratic equation is a polynomial equation with the highest power of 2.
Quadratic formula is a formula to determine the roots/solutions to the equation.

For the example that you are using (3x^2 + 7x - 6 = 0), I got 2/3 & - 3 as the answer when using the quadratic formula. You should get the same answer either way.

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