2. Given X+Y = 5, XY = 8, XY-X-Y =

3.a is the reciprocal of 3 and B is the smallest positive integer, then the algebraic expression 3A2-2AB+ 1 =

4. If (x- 1) 2+| y+2 | = 0, then 2x+3y=

5. When x=, the algebraic expression is meaningless.

6. Given that a+b = 5, the algebraic expression -5 (a+b)+6 (a+b-3)-9 =.

7. The diameter of the great circle is 10 cm. If the diameter of a small circle is 6 cm, then the area of the ring is cm2 (it can be expressed by ∏).

8. When a= and b=. Algebras 4A-3B =

1. When x=2, the value of the following algebraic expression is equal to ().

A.B. C. D。

2. Find the value of the following algebraic expression (which must be carried out in a strict evaluation step)

1. When x = 1 and y = 2, find the value of the following algebraic expression.

( 1) X2+Y2 (2) X2-2xy+Y2 (3)

2. Choose any value of A and B you like, and find the values of algebraic expressions (A+B) (A-B) and A2-B2.

Given the length of 80 wires, bend it into a rectangle. Let one side of it be acm. Then the algebraic expression of this rectangular area is when a= the maximum area and the maximum area is.

3. Additional question: If the value of algebraic expression A2-3A+2 is known to be 4, then the value of algebraic expression 3A2-9A+8.

6.3 Test without brackets

1. Fill in the blanks

( 1)(a-b)+(-c-d)=；

(2)(a-b)-(-c-d)=；

(3)-(a-b)+(-c-d)=；

(4)-(a-b)-(c-d)=；

2. Judge whether the bracket series is correct (tick "√" for the correct one and "×" for the incorrect one):

( 1)a-(b-c)=a-b-c()

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

(3)c+2(a-b)=c+2a-b()

3. In the following brackets, the correct one is ()

a . a2-(2a- 1)= a2-2a- 1 b . a2+(-2a-3)= a2-2a+3

c . 3a-[5 B-(2c- 1)]= 3a-5 b+ 2c- 1d .-(a+b)+(c-d)=-a-b-c+d

4. In the following brackets, the wrong one is ()

a . a2-(3a-2 b+4c)= a2-3a+2 b-4c；

B.4a2+(-3a+2b)=4a2+3a-2b

c . 2 x2-3(x- 1)= 2 x2-3x+3；

D.-(2x-y)-(-x2+y2)=-2x+y+x2-y2

5. Simplify and evaluate the following categories:

( 1)x-(3x-2)+(2x-3)； (2)(3 a2+a-5)-(4-a+7 a2)；

(3)3a2-2(2a2+a)+2(a2-3a)