Meaning: An equation with an unknown number in the denominator is called a fractional equation.

The solution of fractional equation;

① Denominator {Both sides of the equation are multiplied by the simplest common denominator at the same time (the simplest common denominator: ① The coefficient is the least common multiple; (2) the letters that appear occupy the highest power; (3) the factors that appear take the highest power), and the fractional equation is transformed into an integral equation; If you encounter the opposite number. Don't forget to change the symbol.

(2) Find the unknown value according to the steps of solving the integral equation (shift the term, remove the brackets if there are brackets, pay attention to the sign change, merge similar terms, and convert them into 1);

③ Root test (root test is needed after finding the value of the unknown quantity, because in the process of transforming the fractional equation into the whole equation, the range of the unknown quantity is expanded, which may lead to the increase of roots).

Generally speaking, to test the root, we only need to substitute the root of the whole equation into the simplest common denominator. If the simplest common denominator is equal to 0, this root is an increased root, otherwise it is the root of the original fractional equation. If the root of the solution is an increasing root, the original equation has no solution. If the score itself is divided, the score should be tested.

First, multiple-choice questions (3 points for each small question, 30 points for * * *)

1. The following formula is a fraction ()

2. The following calculations are correct ()

3. In the following scores, the simplest score is ()

simplify

The result of is ()

5. If the score

The sum of x in is magnified by 2 times, so the value of the fraction ().

A. Zoom in 2 times. B. Keep it unchanged. C. Zoom out 2 times. D. Zoom out 4 times.