-3x² + 12 = -21x

how does it work ?

-3x² + 12 = -21x

how does it work ?

-21x To right bring then it + 21x .... then you have a zeroing calculation. ..well you share the whole stay in the equation by -3 .... you have to bring it to the root!

simply -21x to the other side bring + 21x

First you have + 21x expected.

Then you can Quadratic Formula / abc-formula / apply pq-formula, because you've got are on one side of 0th

(If you take the pq-formula, you must first nor -3 share).

Quadratic equations to solve the quadratic formula. At first everything on a page ie: -3x² + 21x + 12 = 0th Now insert quadratic formula. Here a link to it: http://www.frustfrei-lernen.de/mathematik/mitternachtsformel.html

-3x ^ 2 + 21x + 12 = 0

Just a side (in the case of the right, by addition) bring to 0

Simplify by Division / 3:

-x ^ 2 + 7x + 4 = 0

here the statement:

-3x² + 12 = -21x / times (-1)

3x²-12 = + 21x / 3

x²-4 = + 7x / -7x

x²-4 -7x = 0

Now you just have to use the Pq formula for further calculations.