Mathematical LIM (x tends to 2) x ^ 2-3x-4 / (x ^ 2-4)

Mathematical LIM (x tends to 2) x ^ 2-3x-4 / (x ^ 2-4)

=LIM (2 ^ 2-3 * 2-4) / (2 * 2-4) = infinite

Find LIM (x tends to 1) x ^ 2-5x + 4 of x ^ 2 + 3x-4

A:
lim(x→1) (x^2+3x-4) / (x^2-5x+4)
=lim(x→1) (x-1)(x+4) / [(x-1)(x-4)]
=lim(x→1) (x+4)/(x-4)
=(1+4) /(1-4)
=-5/3

Let X and y be the two real roots of the equation m2-2am + A + 6 = 0, then the minimum value of (x-1) 2 + (Y-1) 2 is ()
A. -1214B. 18C. 8D. 34

Then (x-1) 2 + (Y-1) 2 = x2 + y2-2 (x + y) + 2 = (x + y) 2-2xy-2 (x + y) + 2 = (2a) 2-2 (a + 6) - 4A + 2 = 4a2-6a-10 = 4 (a-34) 2-494

1、 Fill in the blanks
1. 500 cubic decimeters = () cubic meters 2 liters = () cubic decimeters
2. If the natural number a is 6 times of B, then the least common multiple of a and B is () and the greatest common divisor is ()
3. The maximum true fraction is () and the minimum false fraction is ()
4. There are eight (1 / 8) in 0.8
5. The surface area of the cuboid is (), and the volume is ()
6. Fill in the brackets with a suitable score, > () >
7. () yes. = = () 6
8. Divide the 7 meter long rope into 8 sections, each section is () meters long, accounting for () of the total length
9. There is a cuboid timber with a volume of 540 cubic decimeters and a cross-sectional area of 20 square decimeters. The length of the timber should be ()
10. From the five numbers of 0, 2, 3, 5 and 7, four numbers are selected to form a minimum four digit number which can be divided by 2, 3 and 5 at the same time
11. Fill in ">", "<" or "=" in the 0 of the following questions
（1） ○ （2） ○ 2 （3） ○ 1
2、 Choice
1. A3 means ()
A、a×3 B、a×a×a C、3a
2. The figure below is not a cube expansion, but ()
A、 B、 C、
3. If 2a is added to the numerator, the denominator should be ()
A、2a＋b B、2ab C、3b
4. Fold a piece of rectangular paper in half four times, each of which is () of this paper
A、 B、 C、
5. Is the largest true fraction, then the value of a is ()
A、11 B、1 C、10
3、 Judgment
1. Two different prime numbers must be coprime
2. Different denominator fractions can't be added or subtracted directly because they have different counting units
3. The divisor of a number must be smaller than its multiple
4. There are at least two divisors of any non-zero natural number
5. Because the denominator of contains prime factors other than 2 and 5, it cannot be reduced to a finite decimal

1、 Fill in the blanks
1. 500 cubic decimeter = (0.5) cubic meter 2 liter = (2) cubic decimeter
2. If the natural number a is 6 times of B, then the least common multiple of a and B is (a) and the greatest common divisor is (b)
3. The maximum true fraction is () and the minimum false fraction is ()
4. There are 8 (1 / 10) in 0.8
5. Glue two cubes with 5 cm edge length into a cuboid. The cuboid has a surface area of (250 square cm) and a volume of (250 square cm)
6. Fill in an appropriate score in brackets, > () >. Wrong
7. () yes. = = () 6 wrong
8. Divide the 7 meter long rope into 8 sections, each section is (7 / 8) meters long, accounting for (1 / 8) of the total length
9. There is a cuboid timber with a volume of 540 cubic decimeters and a cross-sectional area of 20 square decimeters. The length of the timber should be (27 decimeters)
10. From the five numbers of 0, 2, 3, 5 and 7, four numbers are selected to form a minimum four digit which can be divisible by 2, 3 and 5 at the same time is (2370)
11. Fill in ">", "<" or "=" in the 0 of the following questions
(1) (2) 2 (3) 1 wrong
2、 Choice
1. A3 stands for (a)
A、a×3 B、a×a×a C、3a
2. The figure below is not a cube expansion, but (). No figure
A、 B、 C、
3. If you add 2a to the numerator, if you want to keep the size of the fraction unchanged, the denominator should be () wrong
A、2a＋b B、2ab C、3b
4. Fold a piece of rectangular paper in half four times, each of which is 1 / 16 of this paper. You didn't write the answer, I filled it in for you
A、 B、 C、
5. Is the largest true fraction, then the value of a is () wrong
A、11 B、1 C、10
3、 Judgment
1. Two different prime numbers must be coprime numbers
2. Fractions with different denominators cannot be added or subtracted directly because they have different counting units
3. The divisor of a number must be smaller than its multiple
4. There are at least two divisors of any non-zero natural number
5. Because the denominator of contains a prime factor other than 2 or 5, it cannot be reduced to a finite decimal

The known circle C1: x2 + Y2 + 2x + 8y – 8 = 0, C2: x2 + Y2 + 4x - 4Y – 2 = 0
I want detailed process, thank you!
It is known that circle C1: x2 + Y2 + 2x + 8y – 8 = 0, C2: x2 + Y2 + 4x - 4Y – 2 = 0.

C1:(x+1)^2+(y+4)^2=25
C2:(x+2)^2+(y-2)^2=10
The center distance of two circles is d = √ [(- 1 + 2) ^ 2 + (- 4-2) ^ 2 = √ 37
r1=5 r2=√10
r1-r2

I have to answer because I'm a teacher

1.45+15×6= 1352.250÷5×8=4003.6×5÷2×4=604.30×3+8=985.400÷4+20×5= 2006.10+12÷3+20=347.(80÷20+80)÷4=218.70+(100-10×5)=1209.360÷40= 910.40×20= 80011.80-25= 5512.70+45=11513.90×2= 18014.16...

A square, side length increased 4 meters, area increased 96 square meters, seek original area!
Requirement is a method that can be used in the third grade

Let the side length be x, equation: (x + 4) ^ 2-x ^ 2 = 96, that is, 8x + 16 = 96, the solution is x = 10 (decimeter), the original area is 100 (square decimeter), that is, 1 square meter

Derivation of period formula of simple pendulum

The reason why high school didn't talk about it is that its derivation, like many formula derivation, needs to use the differential element method mentioned in the competition, which is the rudiment of calculus in university course. For example, the formula of centripetal acceleration is not mentioned. You can refer to the elective part of high school physics textbook to find out the derivation of centripetal acceleration and understand what

The bottom area of a cuboid is a square. Expand the side of the cuboid to form a square with a circumference of 80 cm. Calculate the volume of the cuboid?

According to the fact that the side of the cuboid is a square, the height of the cuboid is 80 / 4 = 20 cm, and the perimeter of the bottom surface of the cuboid is 20 cm, then the side length of the bottom surface is 20 / 4 = 5 cm, the bottom area is 5 * 5 = 25 square cm, and the volume of the cuboid is 25 * 20 = 500 cubic cm

The difference between average speed and average speed

It's not the same
1、 Definition: the average speed is the distance in unit time (the route passed); the average speed is the displacement in unit time (the vector of the first and last positions of the particle in this period)
2、 Velocity has only one size, which is scalar; besides size, velocity has direction, which is the tangent direction of the trajectory curve, which is vector;
3、 Formula: average speed = distance / time; average speed = displacement / time;
☆⌒_ - [hope to help you~