1. If (x+y): (x-y) = 3: 1, then x: y = ().
a、3∶ 1 B、2∶ 1 C、 1∶ 1 D、 1∶2
2. If the solution of equation -2x m=-3 is 3, then the value of m is ().
a、6 B、-6 C、D、- 18
1. Analysis: This question examines the equal deformation of the equation.
From (x+y)∩(x-y)= 3∶ 1, we know that x +y=3(x-y), which is simplified as: x +y=3x-3y.
2x-4y=0, that is, x=2y and x∶y=2∶ 1. Choose B.
2. Analysis: ∫3 is the solution of equation -2x m=-3,
∴-2× 3m =-3,
That is -6 m =-3,
∴ m =-3 6,-According to the basic properties of the equation, 1
∴ m=6, according to the basic properties of Equation 2.
Choose a.3. Junior three students in a school participate in social practice activities. It was originally planned to rent a number of 30-seat buses, but there were still 15 people without seats.
(1) Assuming that the original plan is to rent 30 buses X, try to express the total number of students in the third grade of the school with an algebraic expression containing X;
(2) Now it is decided to rent a 40-seat bus, one less than the original planned 30-seat bus, and one of the rented 40-seat buses is not full and only takes 35 people. Please find out the total number of third-grade students in this school.
Analysis: There are two schemes to show the total number of students in Grade Three. The number of 30 buses is 30x 15.
The total number of people is represented by the number of 40 buses: 40 (x-2) 35.
Solution: (1) The total number of junior three students in our school is 30x 15.
(2) From the meaning of the problem:
30x 15=40(x-2) 35
Solution: x = 6
30x+15 = 30x6+15 =195 (person)
A: There are *** 195 students in Grade Three.
1 、( 3ab-2a)a
2、(x^3-2x^y)÷(-x^2)
3、-2 1a^2b^3÷7a^2b
4、(6a^3b-9a^c)÷3a^2
5、(5ax^2+ 15x)÷5x
6 、( a+2b)(a-2b)
7、(3a+b)^2
8 、( 1/2 a- 1/3 b)^2
9 、( x+5y)(x-7y)
10 、( 2a+3b)(2a+3b)
1 1 、( x+5)(x-7)
12、5x^3×8x^2
13、-3x×(2x^2-x+4)
14、 1 1x^ 12×(- 12x^ 1 1)
15 、( x+5)(x+6)
16 、( 2x+ 1)(2x+3)
17、3x^3y×(2x^2y-3xy)
18、2x×(3x^2-xy+y^2)
19、(a^3)^3÷(a^4)^2
20、(x^2y)^5÷(x^2y)^3
1 、( 3ab-2a)÷a=3b-2
2、(x^3-2x^y)÷(-x^2)=-x+2x^(y-2)
3、-2 1a^2b^3÷7a^2b=-3b^2
4、(6a^3b-9a^c)÷3a^2=2ab-3a^(c-2)
5、(5ax^2+ 15x)÷5x=ax+3
6、(a+2b)(a-2b)=a^2-4b^2
7、(3a+b)^2=9a^2+6ab+b^2
8 、( 1/2 a- 1/3 b)^2= 1/4a^2- 1/3ab+ 1/9b^2
9、(x+5y)(x-7y)=x^2-2xy-35y^2
10、(2a+3b)(2a+3b)=4a^2+ 12ab+9b^2
1 1、(x+5)(x-7)=x^2-2x-35
12、5x^3×8x^2=40x^5
13、-3x×(2x^2-x+4)=-6x^3+3x^2- 12x
14、 1 1x^ 12×(- 12x^ 1 1)=- 132x^23
15、(x+5)(x+6)=x^2+ 1 1x+30
16、(2x+ 1)(2x+3)=4x^2+8x+3
17、3x^3y×(2x^2y-3xy)=6x^5*y^2-9x^4*y^2
18、2x×(3x^2-xy+y^2)=6x^3-2x^2*y+2xy^2
19、(a^3)^3÷(a^4)^2=a
20、(x^2y)^5÷(x^2y)^3=(x^2y)^2=x^4*y^2