I feel the same way. I don't talk much in junior high school, but the high school teacher thinks we will. This is a formula that I don't think was mentioned in junior high school but used in senior high school for reference only:

Vieta's Theorem: Let two roots of a quadratic equation of one variable be X 1 and X2.

Then x1+x2 =-b/a.

X 1*X2=c/a

Cubic sum: a 3+b 3 = (a+b) (a 2-ab+b 2)

Cubic difference: a 3-b 3 = (a-b) (a 2+ab+b 2)

Complete cubic summation formula: a 3+3a 2b+3ab 2+b 3.

Complete cubic difference formula: a 3-3a 2b+3ab 2-b 3

Cross multiplication solution of quadratic equation in one variable;

/view/ 198055.htm

That should be all.