"Removing Brackets" PPT Courseware

Description

"Removing Brackets" PPT Courseware

learning target

(1) Master the rules of bracket removal.

(2) Use the rules to remove brackets correctly as required.

(3) Cultivate observation and induction skills and the ability to consider problems in an all-round way.

Teaching emphasis, difficulty and key

Key point: the rule of bracket removal.

Difficulty: The rule for removing brackets when there is a "-" sign before the brackets.

Create scenarios and introduce topics

Example 1: There were originally a classmates in the library. Later, a certain grade organized students to read. B classmates came in the first batch, and c classmates came in the second batch. Then there are (a+b+c) students in the library. Classmates. We can understand it this way. Later, a total of (b+c) students came back in the two batches, so there were a+(b+c) students in the library. Since a+b+c and a+(b+c) both mean The same quantity, then we get formula (1):

Example 2: There used to be a classmate in the library. After class, the students left the library one after another. The first batch of classmates left, and the second batch of classmates left. C classmates left. Try two methods to write out the remaining students in the library. How many classmates are there?

Test conclusion and formulate rules

Please check whether the two algebraic expressions on the left and right are equal:

(1) 13+ (7-5) 13+7-5

(2) 13-(7-5) 13-7+5

Rules for removing brackets:

a +(-b+c)= a -b +c

There is a "+" sign in front of the brackets. If you remove the brackets and the "+" sign in front of them, the symbols of the items in the brackets will not change.

a－(－b+c)= a-(+b + c)

There is a "-" sign in front of the bracket. Remove the bracket and the "-" sign in front of it, and the symbols of each item in the bracket will be changed.

Achieve standards in class and consolidate practice

1. According to the bracket removal rule, fill in the "+" or "-" sign in ___:

(1)a___(-b+c)=a-b+c (2)a___(b-c-d)=a-b+c+d;

(3) ___(a-b)___(c+d)=c+d-a+b

2. It is known that x+y=2, then x+y+3=______, 5-x-y=______

3. Remove the brackets:

(1) a+3(2b+c-d) (2) 3x-2(3y+2z).

(3)3a+4b-(2b+4a) (4)(2x-3y)-3(4x-2y).

Class Summary Reaching Consensus

1. What is the rule of bracket removal? What should we pay special attention to when removing brackets?

2. When a number is multiplied by a polynomial, this number must be multiplied by each term in the polynomial.

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"Removing Brackets" PPT Courseware 4:

"Removing Brackets" PPT Courseware 4 Do it 1. On Wednesday afternoon, there was a student named A in the school library. Later, a certain grade organized students to read, and the first batch of classmates came, and the second batch of classmates came. Then there are __________ students in the library. 2. Someone brings a..

"Removing Brackets" PPT Courseware 3:

"Removing Brackets" PPT Courseware 3 Exploration Exercise: Calculate and find equal integers a+(b+c) a+(b-c) a-(b+c) a-(b-c) a-b+c a+b+c a+ b-c a-b-c a+(b+c)=a+b+c a+(b-c)=a+b-c a-(b+c)=a-b-c a-(b-c)=a-b+c On the left...

"Removing Brackets" PPT Courseware 2:

"Removing Brackets" PPT Courseware 2 Learning Objectives (1) Master the rules of removing brackets. (2) Use the rules to remove brackets correctly as required. (3) Cultivate observation and induction skills and the ability to consider problems in an all-round way. Teaching important, difficult and key points: removing brackets...

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Update Time: 2024-09-12

This template belongs to Mathematics courseware Qingdao Edition Seventh Grade Mathematics Volume 1 industry PPT template

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