In addition, there are matching method, direct opening method and factorization method. Step 1. Change the equation to the general formula AX 2+BX+C = 0;
2. Determine the discriminant and calculate B2-4ac；;
3. If b 2-4ac ≥ 0, substitute it into the formula X = [-b √ (B2-4ac)]/2a;
If b 2-4ac
Solution: x 2+2x- 1 = 0.
A= 1 B=2 C=- 1
b^2-4ac=2^2-4× 1×[- 1]=4+4=8
Substitute the formula x = [-b √ (b 2-4ac)]/2a, x = [-2 √ 8]/2×1=-1√ 2.
X 1=- 1+√2
X2=- 1-√2
Understandable method
The square 2x+4x-2 for solving the equation = 0.
Solution: the square of x +2x- 1 =0.
This equation is first put into a general form.
A= 1 B=2 C=- 1
The square of B -4ac = 2-4×/kloc-0 /× [-1] = 4+4 = 8.
X=2x 1 point [-2+8] =- 1+2 point is brought in when x=2a plus or minus the root sign (square of b -4ac).
X 1= 1 plus the root number 2.
X2= 1 Subtract the root number 2 [Edit this paragraph] Note: There must be no case where the quadratic equation of one variable cannot be solved by the formula method. (The so-called "general formula of quadratic equation in one variable")
However, if you can directly find the root or factorization, you'd better use the direct open method and factorization method.
Only applicable to junior high schools.