1, column algebra problem.

For example, building A is 24.5 meters higher than building C, and building B is 15.6 meters higher than building C, so how many meters is building B lower than building A?

Solution: If the height of building C is x meters, then the height of building A is (x+ 24.5) meters, the height of building B is (x+ 16.5) meters, and (X+ 16.5)-(x+ 24.5)=-8.9, that is, the height of building B is higher than that of building A.

2. Calculation of rational numbers.

For example, calculate (11998-1) (11997-1) (1/000).

Analysis of test questions: subtraction rule of reverse rational number, multiplication of transformation component number.

Solution: The original formula =-(1997/1998) (1996/1997) (999/1000) =-1/2.

3. Sum and difference problem.

Given the sum and difference of two numbers, find these two numbers.

Formula: sum plus difference, the bigger it becomes; Divided by 2, it is big; And subtract the difference, the smaller the reduction; Divided by 2, it is small.

4, the difference ratio problem.

Formula: I am more than you, and multiple is cause and effect. Actual difference of numerator, multiple difference of denominator. Double the quotient and multiply it by their respective multiples to get two numbers.

Knowledge points and matters needing attention in the mid-term exam of junior one mathematics last semester

1, number axis

The concept of number axis: the straight line defining the origin, positive direction and unit length is called number axis. Three elements of the number axis: origin, unit length and positive direction.

Points on the number axis: All rational numbers can be represented by points on the number axis, but not all points on the number axis represent rational numbers. (Generally, the right direction is the positive direction, and the points on the number axis correspond to any real number, including irrational numbers. )

Compare sizes with the number axis: Generally speaking, when the number axis points to the right, the number on the right is always greater than the number on the left.

2. Inverse number

The concept of inverse number: Only two numbers with different signs are called inverse numbers.

The significance of opposites: master that opposites appear in pairs and cannot exist alone. From the number axis, except for 0, they are two numbers with opposite directions, on both sides of the origin, and the distance from the origin is equal.

Simplification of multiple symbols: No matter the number of "+",the odd number of "﹣" is negative and the even number of "﹣" is positive.