By multiplying the numerator denominator by the same number at the same time, the root sign in the denominator is eliminated, and the denominator becomes a rational number. Usually, the denominator of a molecule is physics and chemistry, and the square difference formula is commonly used, that is, (a+b) * (a-b) = a 2-b 2.

Let's give a quadratic radical with parameters:

will

The denominator is rational:

Here we use the square difference formula to decompose molecules into factors, and then decompose them! Please note that we cannot multiply the denominator here.

, because

It may be equal to 0, and it is more troublesome to discuss it according to the situation. At this time, we should pay attention to the structural relationship between numerator and denominator!

Extended data

Molecules have physical and chemical effects.

1, molecular rationalization can achieve some size comparisons that are difficult to carry out in the standard form by unifying molecules, and sometimes it can greatly simplify some product operations.

2. High school mathematics uses definitions to prove monotonicity.

3. Calculation of the limit of calculus.

Baidu Encyclopedia-Square Difference Formula

Baidu Encyclopedia-The denominator is rationality